1st order laboratory parameters – obligatory laboratory tests (unless otherwise shown).
Blood tests
- Blood count
- ESR (erythrocyte sedimentation rate) or CRP (C-reactive protein).
- Serum calcium
- Serum phosphate
- Serum creatinine, creatinine clearance if applicable.
- Alkaline phosphatase (AP)
- Gamma-GT
- TSH (thyroid-stimulating hormone)
- Serum electrophoresis
- If necessary, hydroxy vitamin D3 (as a case-by-case decision).
- Testosterone in men (optional; according to medical history).
Urine tests (24-h urine).
- Creatinine clearance
- Phosphate and protein excretion in urine
- Crosslinks – deoxypyridinoline (DPD) and pyridinoline (PYD crosslinks) – monitoring bone resorption (osteoporosis) and increased cartilage degradation.
Bone turnover markers (as a case-by-case decision).
- Bone formation marker
- Ostase – bone-specific alkaline phosphatase/bone alkaline phosphatase (BAP =).
- Osteocalcin (OC)
- P1NP (procollagen type 1 N-terminal propeptide)
- PICP (procollagen I carboxy-terminal propeptide)
- 25-(OH)-cholecalciferol and 1.25-di-(OH)-cholecalciferol
- Bone resorption marker
- Β-Crosslaps (β-CTX) – considered a reliable marker of increased bone loss (osteoporosis), especially in postmenopausal women; blood collection for Beta-CrossLaps only fasting between 07:00 and 09:00 a.m.
- TRAP 5b (tartrate-resistant acid phosphatase); due to limited stability, sample must be transported to the laboratory on the same day
- Crosslinks (pyridinoline, deoxypyridinoline) in 1st morning urine; determination in bone metastases (beneficial).
- ICTP – I-carboxyterminal telopeptide.
Cause of disease / laboratory findings | PTH | 25-OH vitamin D (calcifediol) | 1,25-dihydroxyvitamin D (calcitriol) |
End-organ resistance; disruption of receptor function; senile osteoporosis (?). | Increased | Normal | Normal to elevated |
1,25-di-(OH)-cholecalciferol deficiency; renal insufficiency. | Increased | Normal | Degraded |
Primary vitamin D deficiency; dietary vitamin D deficiency; impaired absorption; decreased sun exposure | Increased | Decreased | Degraded |
2nd order laboratory parameters – depending on the results of the medical history, physical examination, etc. – for differential diagnostic clarification
Hormone tests
- Parathyroid hormone (PTH)
- 25-OH cholecaliferol – 25-OH vitamin D
- 17-Beta-estradiol
- Testosterone
- Thyroid hormones – thyroxine (T4) and triiodothyronine (T3)
Molecular genetic testing
Further studies
- Bence Jones protein in urine and urinary immunoelectrophoresis – if plasmocytoma (multiple myeloma) is suspected.
- Calcium excretion in 24-h urine – in hypercalcemia (excess calcium in blood serum).
- Iron status, vitamin B12, folic acid in plasma.
- Homocysteine
- Chymotrypsin in the stool, pancreatic auryl test – for diagnosis of exocrine pancreatic insufficiency (pancreatic hypofunction).
- Transglutaminase antibody or endomysium antibody (EMA) as well as total IgA in serum – as celiac disease screening; in case of IgA deficiency: genetic test (DNA analysis)/detection of celiac disease-associated HLA-DQ gene constellation, this allows with very high certainty the exclusion of celiac disease.