Advanced Metabolic Panel

Glucose is the primary energy substrate for most tissues and the principal fuel for the brain. Its plasma concentration reflects the balance between intestinal absorption, hepatic production (glycogenolysis and gluconeogenesis), and peripheral uptake mediated by insulin and other hormones. Tight glucose regulation is maintained by insulin secretion from pancreatic beta cells in response to rising blood glucose, counterbalanced by glucagon, cortisol, and catecholamines during fasting or stress.

Fasting plasma glucose is a cornerstone diagnostic criterion for diabetes and prediabetes and a front-line screen for dysglycaemia. Persistently elevated glucose signals insulin resistance or beta-cell failure, while very low glucose may indicate insulinoma, adrenal insufficiency, or iatrogenic hypoglycaemia. Glucose is interpreted alongside insulin, HbA1c, and lipid markers to characterise metabolic health.

Insulin is an anabolic peptide hormone secreted by pancreatic beta cells in response to rising plasma glucose and amino acids. It drives glucose uptake into muscle and adipose tissue, suppresses hepatic glucose production, and promotes lipogenesis and protein synthesis. In insulin resistance the tissues require higher insulin concentrations to achieve the same glucose disposal, leading to compensatory hyperinsulinaemia until beta-cell reserve is exhausted.

Fasting insulin is a direct marker of insulin secretion and a sensitive early indicator of insulin resistance, often elevated years before glucose rises into the prediabetic range. Elevated fasting insulin in the setting of normal or mildly elevated glucose is a hallmark of the insulin-resistant state that underpins metabolic syndrome, polycystic ovary syndrome, and non-alcoholic fatty liver disease. Very high insulin with low glucose suggests insulinoma or exogenous insulin administration.

HOMA-IR is a calculated index derived from fasting glucose and fasting insulin using the formula (glucose [mg/dL] × insulin [µU/mL]) / 405. It models the feedback loop between beta-cell insulin secretion and hepatic glucose production, providing a surrogate for clamp-measured insulin sensitivity. Higher values indicate greater resistance.

HOMA-IR quantifies insulin resistance in research and clinical practice, bridging the gap between simple fasting glucose and the gold-standard hyperinsulinaemic-euglycaemic clamp. It is widely used to screen for and track insulin resistance in metabolic syndrome, PCOS, and MASLD, and values above 2.0–2.5 are typically considered insulin-resistant depending on the population.

Haemoglobin A1c is the glycated fraction of adult haemoglobin, formed by non-enzymatic attachment of glucose to the N-terminal valine of the beta chain. The extent of glycation is proportional to the average glucose concentration over the preceding 8–12 weeks, corresponding to the lifespan of circulating erythrocytes. HbA1c provides an integrated measure of glycaemic control unaffected by day-to-day variation.

HbA1c is a diagnostic criterion for diabetes and prediabetes, a monitoring standard for glycaemic control in established diabetes, and a cardiovascular risk marker. Unlike glucose, it does not require fasting and is not subject to acute fluctuation, making it convenient for screening and longitudinal follow-up. Values ≥6.5% confirm diabetes; 5.7–6.4% define prediabetes.

Lipase is a pancreatic enzyme that hydrolyses dietary triglycerides in the small intestine. It is synthesised by pancreatic acinar cells and secreted into the duodenum in response to cholecystokinin. Serum lipase activity rises when acinar-cell injury or ductal obstruction permits enzyme to leak into the circulation. Lipase has a longer half-life than amylase and is more specific for pancreatic disease.

Lipase is the preferred single biochemical marker for acute pancreatitis, more sensitive and specific than amylase. Elevations more than three times the upper limit in the appropriate clinical setting (epigastric pain radiating to the back, nausea, vomiting) strongly support the diagnosis. Modest elevations can occur in other intra-abdominal conditions and renal insufficiency, so lipase is interpreted with imaging and the clinical picture.

Uric acid is the end product of purine nucleotide catabolism in humans, who lack uricase and cannot degrade it further. Two-thirds of uric acid is excreted by the kidneys, where it is freely filtered and then largely reabsorbed and secreted by tubular transporters; the remainder is eliminated via the gut. Serum concentration depends on the balance between purine intake, endogenous production, and renal and intestinal clearance.

Elevated uric acid (hyperuricaemia) predisposes to gout and nephrolithiasis and is an independent risk marker for hypertension, chronic kidney disease, metabolic syndrome, and cardiovascular events. Low uric acid is less common, seen with xanthinuria or hereditary renal hypouricaemia. Uric acid is monitored when initiating urate-lowering therapy for gout and in metabolic risk assessment.

C-reactive protein is an acute-phase reactant synthesised by hepatocytes in response to interleukin-6 and other inflammatory cytokines. High-sensitivity assays measure CRP at concentrations well below the range of traditional inflammation assays, enabling stratification of low-grade chronic inflammation. CRP rises rapidly in acute infection or tissue injury and falls as inflammation resolves.

hs-CRP is a non-specific marker of systemic inflammation used for cardiovascular risk stratification independent of lipid levels, obesity, and metabolic syndrome. Persistently elevated hs-CRP predicts future myocardial infarction and stroke, and trending CRP helps monitor inflammatory conditions such as autoimmune disease. Very high values (>10 mg/L) suggest acute infection or inflammation and should prompt further investigation rather than cardiovascular risk interpretation.