1st order laboratory parameters – obligatory laboratory tests.
- Small blood count
- Inflammatory parameters – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
- Fasting glucose (fasting blood glucose).
- HbA1c (long-term blood glucose value)
- Fasting insulin serum level [determination of insulin resistance: HOMA index (Homeostasis Model Assessment) or insulin resistance score according to Standl/Biermann – see under “Fasting insulin”]Note: insulin and testosterone serum levels are inversely correlated.
- Leptin serum levels
- Thyroid parameters – TSH
- Renal parameters – urea, creatinine, cystatin C or creatinine clearance if necessary; test for microalbuminuria.
- Liver parameters – alanine aminotransferase (ALT, GPT), aspartate aminotransferase (AST, GOT), glutamate dehydrogenase (GLDH), gamma-glutamyl transferase (γ-GT, gamma-GT; GGT), alkaline phosphatase, bilirubin.
- LDL, HDL cholesterol, triglycerides
- Uric acid – adjusted for age, BMI, and glomerular filtration rate, both hyperuricemia and metabolic syndrome were independent risk factors for insulin resistance in women
- Fibrinogen (coagulation parameter).
Laboratory parameters 2nd order – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification.
- Oral glucose tolerance test (oGTT) – test procedure to detect impaired glucose tolerance or diabetes mellitus.
- 24h-collected urine with determination of creatinine [calculated glomerular filtration rate (< 60 ml/min/1.73 m2) or creatinine clearance < 60 ml/min], metanephrine and catecholamines – in the case of suspected pheochromocytoma (usually benign tumor, predominantly originating in the adrenal glands)
- Dexamethasone inhibition test – when Cushing’s syndrome (renal cortical hyperfunction with elevated cortisol) is suspected – quotient of aldosterone to renin – when primary hyperaldosteronism is suspected (Conn’s syndrome; the cause is usually a benign tumor of the adrenal cortex)
- Findings: plasma cortisol < 5 µg/dl on 2 mg dexamethasone short-term test excludes Cushing’s syndrome.
- Aldosterone, renin (due tohypertension / hypertension).
- PTH (parathyroid hormone)
- Electrolytes – calcium, phosphate; magnesium (due tohypertension).
