Lactate-to-albumin ratio, C-reactive protein-to-albumin ratio, and prognostic nutritional index in acute and critical care: A focused mini-review

Table 1 Calculation, units, clinical use, strengths/Limitations, main confounders and cutoff values of albumin-based indices

Index	Formula	Unit or reporting format	Common clinical settings	Strengths and limitations	Main confounders
Lactate to albumin ratio	Serum lactate/serum albumin	Unit dependent ratio. Usually calculated using lactate in mmol/L and albumin in g/dL or g/L. The units used in calculation should be clearly reported	Sepsis and septic shock, emergency department populations, intensive care unit patients, out-of-hospital cardiac arrest, acute pancreatitis, gastrointestinal bleeding, cardiovascular emergencies, respiratory failure, trauma, and postoperative critical care	Reflects the interaction between metabolic stress, tissue hypoperfusion, lactate clearance, and albumin-related physiological reserve. However, its performance varies across disease groups, and cutoff values are not uniform	Hepatic dysfunction, renal dysfunction, impaired lactate clearance, adrenergic stress, vasopressor use, fluid resuscitation, hemodilution, albumin replacement, blood loss, and timing of measurement
C-reactive protein to albumin ratio	C-reactive protein/serum albumin	Unit dependent ratio. Usually calculated using C-reactive protein in mg/L or mg/dL and albumin in g/dL or g/L. The units used in calculation should be clearly reported	Sepsis and septic shock, acute pancreatitis, appendicitis, cholangitis, inflammatory bowel disease, postoperative infection, pneumonia, COVID-19, chronic obstructive pulmonary disease, cardiovascular diseases, trauma, geriatric emergency patients, and malignancy	Combines systemic inflammatory burden with albumin-related biological reserve. However, CRP is nonspecific, and the incremental value of CAR beyond established clinical scores may vary	Chronic inflammatory disease, malignancy, older age, autoimmune disease, sterile inflammation, recent surgery or trauma, hepatic dysfunction, hypoalbuminemia, fluid overload, hemodilution, and timing of CRP measurement
Prognostic nutritional index	10 × serum albumin (g/dL) + 0.005 × total lymphocyte count (/mm3)	Dimensionless score	Oncology, gastrointestinal surgery, perioperative care, sepsis, intensive care unit patients, acute pancreatitis, gastrointestinal bleeding, liver transplantation, pneumonia, COVID-19, cardiovascular diseases, and stroke	Reflects immune-nutritional vulnerability through albumin and lymphocyte count. However, in acute illness, PNI may reflect inflammation and disease severity rather than nutritional status alone. Thresholds may not generalize across populations	Systemic inflammation, acute physiological stress, corticosteroid exposure, infection, malignancy, chronic immune dysfunction, hepatic dysfunction, malnutrition, fluid balance, hemodilution, and baseline lymphocyte abnormalities

CRP: C-reactive protein; COVID-19: Coronavirus disease 2019; CAR: C-reactive protein-to-albumin ratio; PNI: Prognostic nutritional index.