Serum prealbumin and C-reactive protein levels to evaluate parenteral nutrition efficacy in critically ill patients with gastrointestinal tumors

Abstract

BACKGROUND

Evaluating the efficacy of parenteral nutrition support and providing a reference for postoperative nutritional support in patients undergoing surgery for gastrointestinal tumors is important.

AIM

To investigate the value of combined detection of serum prealbumin (PA) and C-reactive protein (CRP) in assessing the efficacy of parenteral nutrition support for critically ill patients with gastrointestinal tumors, and to provide an evidence-based reference for clinical precision.

METHODS

This retrospective study comprised clinical data concerning 186 critically ill patients with gastrointestinal tumors admitted to the Surgical Ward of Putuo Hospital, Shanghai University of Traditional Chinese Medicine, from August 2023 to August 2025. All patients underwent radical gastrointestinal tumor resection and received total parenteral nutrition support on postoperative day (POD) 1. Venous blood samples were collected from patients before nutritional support, and thereafter on PODs 1, 3, 7, and 14 of parenteral nutrition support to measure serum PA, CRP, albumin (ALB), transferrin (TF), and interleukin-6 (IL-6) levels. According to the efficacy of parenteral nutrition support on POD14, we divided the patients into an effective or ineffective support groups. Between-group differences in serum indicators and prognostic outcomes were compared. A receiver operating characteristic curve was used to evaluate the value of serum indicators in assessing and effectively predicting the efficacy of parenteral nutrition support.

RESULTS

Of 186 critically ill patients with gastrointestinal tumors, after 14 days of parenteral nutrition support, 32 (17.20%) patients had ineffective nutritional support and 154 (82.80%) had effective nutritional support. On POD1 and POD3 of parenteral nutrition support, serum PA, ALB, and TF levels in both groups were significantly lower than those prior to nutritional support (P < 0.05). In both groups, these levels were significantly increased on POD7 and POD14, compared with those on POD1 and POD3 (P < 0.05). In the effective support group, serum PA, ALB, and TF levels were significantly higher than those in the ineffective support group on POD7 and POD14 (P < 0.05). On POD1 and POD3, serum CRP and IL-6 levels in both groups were significantly higher than those before nutritional support (P < 0.05). In both groups, these levels were significantly decreased on POD7 and POD14, compared with those on POD1 and POD3 (P < 0.05). Serum CRP and IL-6 levels in the effective support group were significantly lower than those in the ineffective support group on POD7 and POD14 (P < 0.05). The time to first flatus, gastric emptying time, time to resumption of normal diet, and hospital stay in the effective support group were significantly shorter than those in the ineffective support group (P < 0.05). With serum PA and CRP levels on POD7 and POD14 of nutritional support as independent variables and the efficacy of parenteral nutrition support as the dependent variable, the efficacy of combined detection of serum PA and CRP in predicting the efficacy of parenteral nutrition support was significantly higher than that of single serum indicators (P < 0.05). The predictive efficacy of serum indicators on POD14 was slightly higher than that POD7, with no statistically significant difference (P > 0.05).

CONCLUSION

Dynamic monitoring of changes in serum PA and CRP levels can effectively evaluate the nutritional status and inflammatory level of critically ill patients with gastrointestinal tumors after parenteral nutrition support. The combined detection of serum PA and CRP levels can accurately predict the efficacy of parenteral nutrition support in such patients, providing a reliable reference for the adjustment of clinical nutritional support regimens.

Key Words: C-reactive protein; Critical illness; Gastrointestinal tumor; Parenteral nutrition support; Prealbumin

Core Tip: This study demonstrates that dynamic monitoring of serum prealbumin and C-reactive protein levels can effectively assess the nutritional and inflammatory status of critically ill gastrointestinal tumor patients after parenteral nutrition. The combined detection of these two indicators enables precise prediction of parenteral nutrition efficacy, providing a reliable reference for adjusting clinical nutritional support strategies.

INTRODUCTION

Gastrointestinal tumors are common malignant tumors in clinical practice with high morbidity and mortality rates, including gastric cancer, esophageal cancer, colorectal cancer, and malignant tumors of the hepatobiliary and pancreatic system. Their development is associated with genetic factors, dietary habits, chronic inflammation, and other conditions[1,2]. At present, the incidence of gastrointestinal tumors remains persistently high. According to global cancer statistics[3], gastrointestinal tumors account for one-fourth of the overall incidence of malignant tumors and one-third of cancer-related mortality. China bears a heavy burden of gastrointestinal tumors, with as many as 1922362 newly diagnosed cases and 1497388 cancer-related deaths annually, making it a major disease threatening the health of the Chinese population[4]. With the improvement of public health awareness and medical standards, the early detection rate of gastrointestinal tumors has increased significantly. Surgery is the first-line treatment for early-stage gastrointestinal tumors. However, patients with gastrointestinal tumors generally present with symptoms such as dyspepsia, anorexia, and emaciation. In addition, surgical trauma, perioperative complications, metabolic disorders, and other factors can further exacerbate nutritional deficiencies in these patients[5]. Particularly for critically ill patients with gastrointestinal tumors, their impaired immune function, enhanced stress response, and a state of high metabolism and catabolism further increase the risk of postoperative complications and adversely affect patient prognosis[6]. Therefore, early nutritional support should be administered postoperatively to critically ill patients with gastrointestinal tumors. Parenteral nutrition support is a commonly used nutritional intervention for such patients after surgery and plays a crucial role in improving their postoperative nutritional status[7]. However, some patients fail to benefit from parenteral nutrition support, leading to poor prognostic outcomes. Accurately evaluating the efficacy of postoperative parenteral nutrition support and implementing corresponding intervention strategies at an early stage have thus become key research priorities. Prealbumin (PA) and C-reactive protein (CRP) levels are routinely used clinical indicators reflecting the body's nutritional status and indicating the inflammatory state, respectively. It is therefore of considerable exploratory value to investigate whether the combined detection of these two indicators can effectively evaluate the therapeutic efficacy of parenteral nutrition support. This study aimed to investigate the value of combined detection of serum PA and CRP in assessing the efficacy of parenteral nutrition support for critically ill patients with gastrointestinal tumors, and to provide an evidence-based reference for clinical precision nutritional support. The findings are reported as follows.

MATERIALS AND METHODS

General information

A retrospective study was conducted to collect clinical data concerning 186 critically ill patients with gastrointestinal tumors admitted to the Department of Surgery, Putuo Hospital, Shanghai University of Traditional Chinese Medicine from August 2023 to August 2025.

Inclusion criteria: (1) With pathologically and clinically confirmed gastrointestinal tumors; (2) Eligible for surgical resection with clear operative indications; (3) With clear consciousness; (4) With an Acute Physiology and Chronic Health Evaluation II score ≥ 20 points[8]; (5) With an inability to ingest nutrition via the gastrointestinal tract or insufficient enteral nutrition intake, requiring parenteral nutrition support; and (6) With complete clinical data.

Exclusion criteria: (1) Severe infections such as bacteremia and respiratory system infection; (2) Hepatic and renal insufficiency, or severe cardiovascular and cerebrovascular diseases; (3) Congenital amino acid metabolism disorders; (4) Contraindications to parenteral nutrition support; and (5) Immunodeficiency diseases and coagulation disorders.

Severe infection was identified according to documented clinical diagnoses recorded in the electronic medical record system, including bacteremia, sepsis, severe pneumonia, or other infections requiring systemic antimicrobial treatment. Immunodeficiency disorders were identified based on documented medical history, specialist diagnoses, or long-term immunosuppressive therapy recorded in hospital records.

Methods

Protocol for parenteral nutrition support: All patients received parenteral nutrition support, with the nutritional preparations including a compound amino acid injection, fat emulsion injection, glucose injection, vitamin preparations, and mineral preparations. The daily caloric supply was 100-125 kJ/kg, with energy derived from glucose and conventional fat emulsion (accounting for 40%-50% of total energy). The daily nitrogen supply was 0.15-0.20 g/kg. Additional supplements included water-soluble vitamins, fat-soluble vitamins, trace elements, glutamine, ω-3 unsaturated fatty acids and arginine, with a total daily intake of 20 g for the supplements. All nutritional preparations were formulated into a parenteral nutrition solution and infused via a central or peripheral venous catheter. Half of the total daily supply was administered on postoperative day (POD) 1, and the full dose was given from POD2, with the duration of parenteral nutrition support being no less than 14 days.

Detection methods for serum indicators: For all patients, 3 mL of EDTA-K2 anticoagulated blood and 5 mL of non-anticoagulated whole blood were collected prior to parenteral nutrition support and on POD1, POD3, POD7, and POD14. CRP in EDTA-K2 anticoagulated blood was detected using immunoturbidimetry and a specific protein analyzer (Lifotronic PA-990pro). Non-anticoagulated whole blood was centrifuged for 10 minutes (centrifugal radius, 15 cm; rotation speed, 3500 rpm) after coagulation, and the upper serum was extracted. Interleukin-6 (IL-6) level was detected using a fully automatic chemiluminescence analyzer (Norman NRM411-S7), and serum PA, albumin (ALB), and transferrin (TF) levels were measured using a fully automatic biochemical analyzer (Siemens Atellica CH).

Outcome measures

Evaluation of the efficacy of parenteral nutrition support: The efficacy of parenteral nutrition support was comprehensively evaluated for all patients on POD14, based on an improvement of nutritional status. We defined effective support as no parenteral nutrition-related complications occurrence in the patients, gradual gastrointestinal function recovery, an increase in the serum PA level of > 30 mg/L compared with baseline, and an increase in the serum ALB level of 5 g/L compared with baseline. We defined ineffective support as no improvement or deterioration in a patient's condition; the occurrence of complications such as infection, intestinal obstruction, or the development of a stress ulcer; or failure to meet the above effective criteria for serum PA and ALB levels. The cutoff value of an increase in serum PA > 30 mg/L was selected based on previous studies evaluating short-term nutritional response in critically ill patients, which was considered to represent a clinically meaningful improvement in protein nutritional status.

Serum PA, ALB, and TF levels: Patients were divided into either an effective or ineffective support group, according to the efficacy of parenteral nutrition support. Serum PA, ALB, and TF levels were compared between the two groups prior to parenteral nutrition support and on PODs 1, 3, 7, and 14.

Serum CRP and IL-6 levels: Serum CRP and IL-6 levels were compared between the two groups before parenteral nutrition support and on PODs 1, 3, 7, and 14.

Gastrointestinal function recovery: The time to first flatus, gastric emptying time, time to resumption of normal diet, and hospital stay were recorded for the two groups postoperatively.

Clinical efficacy of serum PA and CRP levels in predicting the effective rate of parenteral nutrition support: Receiver operating characteristic (ROC) curves were plotted to compare the area under the curve, the sensitivity and specificity of individual indicators, and their combination in predicting the efficacy of parenteral nutrition support.

Statistical analysis

All study data were processed using SPSS 26.0 statistical software. Measurement data conforming to a normal distribution were expressed as mean ± SD and analyzed using an independent samples t-test, and comparisons of intra-group data at different time points were performed using repeated measures analysis of variance (ANOVA). Count data are expressed as n (%) and were analyzed using a χ² test. A ROC curve was used to evaluate the value of different indicators in assessing the efficacy of parenteral nutrition support. A two-sided P < 0.05 was considered statistically significant.

RESULTS

Efficacy of parenteral nutrition support

After 14 days of parenteral nutrition support in 186 critically ill patients with gastrointestinal tumors, 32 (17.20%) patients had ineffective support and 154 (82.80%) had effective support. No statistically significant differences in baseline clinical data were observed between the two groups (P > 0.05, Table 1).

Table 1 Comparison of baseline characteristics between the two patient groups, mean ± SD.

Characteristics	Ineffective group (n = 32)	Effective group (n = 154)	χ2/t value	P value
Sex			0.292	0.589
Male	18	130
Female	14	124
Age (year)	60.68 ± 4.81	61.13 ± 5.04	0.478	0.633
Body mass index (kg/m2)	20.88 ± 1.36	21.07 ± 1.40	0.716	0.475
Tumor type			0.206	0.977
Gastric cancer	11	54
Esophageal cancer	8	41
Colorectal cancer	10	48
Other	3	11
Clinical stage			0.010	0.995
Stage I	9	42
Stage II	15	73
Stage III	8	39
Hypertension	6	18	0.631	0.427
Diabetes mellitus	5	12	1.128	0.288
Nutritional Risk Screening 2002 score	4.48 ± 1.05	4.52 ± 1.10	0.194	0.846
Operative time (minute)	252.68 ± 38.48	248.69 ± 41.67	0.526	0.599

Comparison of serum PA, ALB, and TF levels between the two groups: No significant differences in serum PA, ALB, and TF levels were observed between the two groups prior to nutrition support (P > 0.05). On POD1 and POD3 of parenteral nutrition support, serum PA, ALB, and TF levels in both groups were significantly lower than those prior to nutritional support (P < 0.05). On POD7 and POD14, the above indicators in both groups were significantly increased compared with those on POD1 and POD3 (P < 0.05), and serum PA, ALB, and TF levels in the effective support group were significantly higher than those in the ineffective support group POD7 and POD14 (P < 0.05, Table 2).

Table 2 Comparison of serum prealbumin, albumin, and transferrin levels between the two groups, mean ± SD.

Group	Parameter	Prior to nutritional support	POD1	POD3	POD7	POD14	F value	P value
Effective group (n = 154)	PA (mg/L)	231.14 ± 25.84	198.41 ± 18.31	205.60 ± 20.74	234.84 ± 23.67a	251.86 ± 23.14a	147.478	< 0.001
	ALB (g/L)	38.81 ± 3.04	32.12 ± 2.48	33.76 ± 2.63	39.08 ± 2.92a	45.82 ± 3.14a	546.320	< 0.001
	TF (g/L)	2.18 ± 0.21	1.91 ± 0.24	1.93 ± 0.35	2.48 ± 0.27a	3.10 ± 0.30a	484.259	< 0.001
Ineffective group (n = 32)	PA (mg/L)	228.84 ± 26.36	195.74 ± 20.63	202.60 ± 18.75	206.64 ± 18.74	210.14 ± 21.63	10.773	< 0.001
	ALB (g/L)	38.63 ± 2.84	31.92 ± 2.53	33.08 ± 2.70	36.17 ± 2.41	37.08 ± 2.78	35.518	< 0.001
	TF (g/L)	2.19 ± 0.20	1.90 ± 0.24	1.91 ± 0.26	2.12 ± 0.30	2.18 ± 0.29	9.785	< 0.001

^aP < 0.05 vs the invalid group.

ALB: Albumin; PA: Prealbumin; POD: Postoperative day; TF: Transferrin.

Comparison of serum CRP and IL-6 levels between the two groups: No significant differences were observed in serum CRP and IL-6 levels between the two groups prior to parenteral nutrition support (P > 0.05). On POD1 and POD3 of parenteral nutrition support, serum CRP and IL-6 levels in both groups were significantly higher than the baseline levels (P < 0.05). On POD7 and POD14, these levels were significantly decreased in both groups compared with those on POD1 and POD3 (P < 0.05), and serum CRP and IL-6 levels in the effective support group were significantly lower than those in the ineffective support group on POD7 and POD14 (P < 0.05, Table 3).

Table 3 Comparison of serum C-reactive protein and interleukin-6 levels between the two groups, mean ± SD.

Group	Index	Prior to nutritional support	Nutritional support POD1	Nutritional support POD3	Nutritional support POD7	Nutritional support POD14	F value	P value
Effective group (n = 154)	CRP (mg/L)	12.93 ± 2.84	42.41 ± 3.15	38.82 ± 4.20	23.47 ± 2.20a	14.61 ± 2.12a	3166.461	< 0.001
	IL-6 (pg/mL)	13.69 ± 3.14	48.85 ± 4.82	46.65 ± 4.75	28.80 ± 2.73a	21.13 ± 2.49a	2672.053	< 0.001
Ineffective group (n = 32)	CRP (mg/L)	13.10 ± 2.96	41.47 ± 4.50	39.40 ± 4.85	33.12 ± 3.36	30.28 ± 3.60	262.806	< 0.001
	IL-6 (pg/mL)	14.08 ± 3.26	50.13 ± 5.15	47.47 ± 5.63	41.76 ± 3.25	40.50 ± 3.08	371.791	< 0.001

^aP < 0.05 vs the invalid group.

CRP: C-reactive protein; IL: Interleukin; POD: Postoperative day.

Gastrointestinal function recovery outcomes: The time to first flatus, gastric emptying time, time to resumption of normal diet, and hospital stay in the effective support group were significantly shorter than those in the ineffective support group (P < 0.05, Table 4).

Table 4 Comparison of gastrointestinal function recovery between the two groups (day), mean ± SD.

Group	First exhaust time	Gastric emptying time	Normal meal times	Hospital length of stay
Effective group (n = 154)	2.14 ± 1.51	8.82 ± 2.49	10.40 ± 3.28	24.63 ± 2.78
Ineffective group (n = 32)	3.08 ± 1.75	15.73 ± 2.60	14.10 ± 3.36	28.75 ± 3.63
t value	3.115	14.177	5.782	7.212
P value	0.002	< 0.001	< 0.001	< 0.001

Predictive value of serum PA and CRP levels for the efficacy of parenteral nutrition support: With serum PA and CRP levels on POD7 and POD14 of nutrition support as independent variables and the efficacy of parenteral nutrition support as the dependent variable, the predictive efficacy of the combination of serum PA and CRP for the efficacy of parenteral nutrition support was significantly higher than that of a single serum indicator (P < 0.05). The predictive efficacy of serum indicators on POD14 was slightly higher than that on POD7, with no statistically significant difference (P > 0.05, Tables 5 and 6; Figure 1).

Figure 1 Receiver operating characteristic curve. A: Receiver operating characteristic (ROC) curve of serum markers on postoperative day (POD) 7 for the efficacy of parenteral nutrition support; B: ROC plot of serum indicators on POD14 of nutritional support for the efficiency of parenteral nutrition support. CRP: C-reactive protein; PA: Prealbumin.

Table 5 Predictive power of serum biomarkers on postoperative day 7 for the efficacy rate of parenteral nutrition support.

Serum indicators	AUC	Sensitivity (%)	Specificity (%)	P value	SE	95%CI
Serum PA	0.677	65.60	64.30	0.012	0.0464	0.586-0.768
Serum CRP	0.711	56.25	81.17	0.010	0.0587	0.596-0.826
Serum PA combined with CRP	0.900	78.10	88.30	-	0.0294	0.843-0.958

AUC: Area under the curve; CRP: C-reactive protein; PA: Prealbumin.

Table 6 Predictive efficacy of serum markers on postoperative day 14 of nutritional support for the efficacy rate of parenteral nutrition support.

Serum indicators	AUC	Sensitivity (%)	Specificity (%)	P value	SE	95%CI
Serum PA	0.698	75.00	72.73	0.008	0.0462	0.608-0.789
Serum CRP	0.727	59.38	97.40	0.006	0.0647	0.600-0.854
Serum PA combined with CRP	0.956	87.50	93.50	-	0.0187	0.920-0.993

AUC: Area under the curve; CRP: C-reactive protein; PA: Prealbumin.

DISCUSSION

Gastrointestinal tumors rank among the most common malignant tumors worldwide. In particular, with changes in people’s living standards, dietary structures, and social stress, their incidence has been rising and showing an increasingly younger trend. Surgery is the first-line treatment for gastrointestinal tumors, yet patients with such tumors are at risk of malnutrition attributable to tumor-related catabolism, eating disorders, and other factors. In addition, surgical trauma, inflammatory responses, and postoperative complications can further impair nutritional status and exacerbate malnutrition[9,10]. Therefore, timely nutritional support is essential for critically ill patients with gastrointestinal tumors after surgery. Parenteral nutrition support is a cost-effective nutritional intervention for patients who cannot tolerate enteral nutrition or have gastrointestinal dysfunction postoperatively. Intravenously infusing various nutrients and immunonutritional preparations can effectively improve nutritional status, regulate inflammatory responses, reduce oxidative stress, and promote faster postoperative recovery[11]. However, as a result of hypermetabolism, disrupted nitrogen balance, and individual differences in critically ill patients with gastrointestinal tumors, some patients show no response to parenteral nutrition support, resulting in poor support efficacy and adverse prognostic outcomes. Therefore, adopting sensitive and reliable indicators to assess the efficacy of nutritional support can enable clinicians to adjust support regimens in a timely manner and thus improve patient prognosis.

Among 186 critically ill patients with gastrointestinal tumors receiving 14 days of parenteral nutrition support, the ineffective support rate was 17.20% and the effective support rate was 82.80%, indicating that some patients still had no response to nutritional support with poor improvement in nutritional status. PA, ALB, and TF levels are key indicators reflecting the body’s nutritional status. Our findings indicated that serum PA, ALB, and TF levels in both groups on POD1 and POD3 of parenteral nutritional support were significantly lower than those prior to support (P < 0.05), suggesting that patients’ nutritional status deteriorated significantly in the short term postoperatively. As an invasive procedure, surgery causes significant stress injury to the body, leading to a marked decline in nutritional levels. With the extension of nutritional support duration, patients’ nutritional status improved in both groups; however, serum PA, ALB, and TF levels in the effective support group were significantly higher than those in the ineffective support group on POD7 and POD14 (P < 0.05), indicating that patients with no response to parenteral nutrition support had insignificant improvement in nutritional status. Serum PA is an acute-phase reactant with a short half-life (approximately 2 days), is mainly synthesized in the liver, and can reflect the body’s protein anabolism and effectively evaluate short-term nutritional status[12]. Pardo et al[13] reported that dynamic serum PA level monitoring during nutritional support in critically ill patients in intensive care can effectively predict the risk of death, which is closely correlated with energy intake, nitrogen balance, and protein intake levels. Zhang et al[14] reported a close association between serum PA levels and survival time in patients with gastric cancer, and that the serum PA level can serve as an independent prognostic marker. Therefore, a decrease in serum PA levels indicates insufficient nutritional intake, a state of negative nitrogen balance, or severe inflammatory stress and malnutrition in the body, which in turn impairs the hepatic synthesis of PA, leading to a further reduction in serum PA levels. Severe malnutrition and a negative nitrogen balance can adversely affect patient survival prognosis and increase the risk of postoperative complications[15]. ALB is a plasma protein synthesized in the liver with a long half-life (approximately 20-21 days), and is mostly used as an indicator to evaluate the efficacy of long-term nutritional support[16]. TF has a half-life (7-10 days) shorter than ALB but longer than serum PA. In patients with gastrointestinal tumors, tumor-related catabolism, insufficient nutritional intake, and postoperative trauma can all reduce ALB and TF levels[17]. However, their long half-lives make them ineffective indicators for short-term nutritional support. In contrast, serum PA has a higher monitoring sensitivity than ALB and TF, can dynamically assess nutritional status after nutritional support, and is of great significance for evaluating patient prognostic outcomes.

CRP and IL-6 levels are important indicators reflecting the body’s inflammatory response. Our findings indicated that, in both groups, serum CRP and IL-6 levels on POD1 and POD3 of nutritional support were significantly higher than those prior to support (P < 0.05), indicating a marked exacerbation of inflammatory responses in the short-term postoperatively, which was considered to be associated with surgery, anesthesia, and preoperative fasting. Nevertheless, with the extension of nutritional support duration, serum inflammatory responses decreased in both groups, and serum CRP and IL-6 levels in the effective support group were significantly lower than those in the ineffective support group on POD7 and POD14 (P < 0.05). This finding suggests that prolonged parenteral nutrition support improves nutritional status and reduces inflammatory responses, while patients with no response to parenteral nutrition support show insignificant reduction in serum inflammatory responses. Wunderle et al[18] reported that inflammation is a key driver of disease-related malnutrition, which can induce anorexia, reduce food intake, and cause muscle wasting and insulin resistance, leading to a state of hyper-catabolism in the body. CRP levels can be used to identify patients with poor nutritional response. Serum CRP is an acute-phase reactant reflecting the body’s inflammatory response and is synthesized in the liver; its levels rise sharply in response to inflammatory stimuli and traumatic injury[18,19]. IL-6 is a proinflammatory cytokine with high accuracy in evaluating the body’s inflammatory state. Elevated inflammatory responses can promote the metabolism of muscle protein, thereby reducing muscle and fat mass, impairing hepatic synthesis of PA, ALB, and other proteins, and exacerbating malnutrition[20,21]. CRP is a commonly used clinical inflammatory indicator with simple detection procedures, which can be widely carried out in primary hospitals and is therefore often used as a routine blood screening indicator. It has a short half-life: Its levels start to rise 6-8 h after trauma, inflammation, or stress, with a peak at 24-48 hours; therefore, CRP levels can effectively reflect the body’s inflammatory state at this time[22,23]. Elevated CRP levels indicate that the liver may prioritize CRP synthesis, which correspondingly inhibits the synthesis of nutrition-related proteins, impairs the efficiency of protein utilization in the body, and results in insufficient nutritional intake in patients[24,25].

Time to first flatus, gastric emptying time, time to resumption of normal diet, and hospital stay in the effective support group were significantly shorter than those in the ineffective support group (P < 0.05). This result further confirms that patients with a positive response to parenteral nutrition support have improved nutritional status and reduced serum inflammatory responses, which can accelerate postoperative recovery and is important in improving prognostic outcomes. The predictive efficacy of the combination of serum PA and CRP levels for the efficacy of parenteral nutrition support was significantly higher than that of a single serum indicator (P < 0.05), and the predictive efficacy of serum indicators on POD14 was slightly higher than that on POD7, but this difference was not statistically significant (P > 0.05). This indicates that the combination of serum PA and CRP can improve the diagnostic accuracy for the efficacy of parenteral nutrition support. Single indicator detection is influenced by multiple factors such as tumors, drugs, and surgical trauma, leading to insufficient diagnostic specificity; thus, the effective combination of the two indicators can more accurately assess the efficacy of nutritional support for such patients. Since the evaluation outcome of this study was based on the nutritional and inflammatory status on POD14, serum PA and CRP levels on this day can more effectively reflect patients’ nutritional status. Clinicians can evaluate the efficacy of parenteral nutrition support according to serum nutritional and inflammatory indicators, which provides a basis for the clinical adjustment of nutritional support regimens in the later stage. This study had some limitations. This was a single-center retrospective study with a relatively limited sample size, which may introduce selection bias and restrict the generalizability of our findings. Multicenter prospective studies with larger cohorts are needed to further validate the clinical applicability of the results. There was a marked imbalance between the effective group (n = 154) and the ineffective group (n = 32). While ROC analysis indicated excellent predictive performance of the combined PA and CRP model, internal validation procedures such as bootstrap resampling or cross-validation were not performed. Therefore, the possibility of model overfitting and overestimation of predictive performance cannot be completely excluded. The evaluation criteria for nutritional support efficacy partially relied on changes in serum nutritional biomarkers. Since serum PA and ALB levels were also components of the efficacy assessment, a degree of circularity may exist when these markers were subsequently used as predictors of nutritional support efficacy. We did not systematically assess the actual quality of nutritional support delivery, including caloric target achievement, protein intake adequacy, infusion interruptions, and adherence to nutritional prescriptions. Consequently, differences in nutritional delivery between the groups may have influenced the observed treatment responses and cannot be completely ruled out as potential confounding factors. Only short-term outcomes during POD14 were evaluated. Long-term clinical outcomes, including postoperative complication, survival, quality of life, and readmission rates, were not investigated. Future studies should incorporate longer follow-up periods to comprehensively evaluate the prognostic value of serum PA and CRP monitoring. As this was a retrospective study, the identification of severe infection and immunodeficiency conditions relied on the accuracy and completeness of electronic medical records. Therefore, potential misclassification bias cannot be entirely excluded.

CONCLUSION

Parenteral nutrition support is a commonly used nutritional intervention for patients with gastrointestinal tumors after surgery. Dynamic monitoring of changes in serum PA and CRP levels during nutritional support can effectively evaluate the nutritional status and inflammatory level of critically ill patients with gastrointestinal tumors after parenteral nutrition support. The effective combination of serum PA and CRP can accurately predict the efficacy of parenteral nutrition support, evaluate the effect of nutritional therapy, and identify patients with no response to parenteral nutrition support in a timely manner, thus providing a reliable reference for the adjustment of clinical nutritional support regimens.