Laboratory parameters of the 1st order – obligatory laboratory tests.
- Hormone diagnostics
- Total testosterone (see “Important note” below).
- SHBG (sex hormone binding globulin) [with advancing age SHBG ↑ → bioavailable (metabolically active) testosterone ↓]
- LH (luteinizing hormone)
- Prolactin
- TSH
- IGF-1 (insulin-like growth factor), DHEA-S dehydroepiandrosterone sulfate), estradiol, if applicable.
- Small blood count
- Atherosclerosis parameters:
- Total cholesterol, LDL cholesterol, HDL cholesterol.
- Triglycerides
- Homocysteine
- Liver parameters – alanine aminotransferase (ALT, GPT), aspartate aminotransferase (AST, GOT), glutamate dehydrogenase (GLDH) and gamma-glutamyl transferase (gamma-GT, GGT), alkaline phosphatase, bilirubin.
- PSA (prostate specific antigen).
Laboratory parameters 2nd order – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification.
- Inflammatory parameters – CRP (C-reactive protein) or ESR (erythrocyte sedimentation rate).
- Urine status (rapid test for: pH, leukocytes, nitrite, protein, glucose, ketone, urobilinogen, bilirubin, blood), sediment, if necessary urine culture (pathogen detection and resistogram, that is, testing suitable antibiotics for sensitivity / resistance).
- Fasting glucose (fasting blood glucose), if necessary oral glucose tolerance test (oGTT).
- Thyroid parameters – TSH
- Renal parameters – urea, creatinine, cystatin C or creatinine clearance, if necessary.
- Vitamins D3, B6, B12, folic acid, trace elements selenium and zinc.
- Test for occult (not visible) blood in the stool.
Important notice. For the detection of testosterone deficiency, at least two hormone tests (total testosterone and SHBG (sex hormone-binding globulin) and free – metabolically active – testosterone, respectively) are required on two days at the same time – always in the morning between 8.00 and 11.00 am – to adequately take into account deviating individual findings and the daily fluctuations in serum levels.
It is also essential to check serum prolactin levels, since hyperprolactinemia (elevated prolactin levels in the blood) can lead to a marked testosterone deficiency due to a decrease in FSH (follicle-stimulating hormone) and LH (luteinizing hormone).
