Disorder | Serum phosphate | Serum calcium | Serum alkaline phosphatase | Parathyroid hormone | 25-hydroxyvitamin D* | 1,25-dihydroxyvitamin D |
Vitamin D deficiency | ↓ or N | ↓ or N | N or ↑ | ↑ | ↓↓ | N or ↑ or ↓ |
Conditions associated with urinary phosphate wasting | ↓↓ | N | N or ↑ | N¶ | N or ↓ | N or ↑ or ↓ |
Proximal renal tubular acidosisΔ | ↓ | N | N | N or ↑ | N or ↓ | N |
Hypophosphatasia | N | N | ↓ | N | N or ↓ | N |
Osteogenesis imperfecta and axial osteomalacia | N | N | N or ↑ | N | N or ↓ | N |
Osteoporosis | N | N | N | N | N or ↓ | N |
Chronic kidney disease | N or ↑ | N or ↑ or ↓ | N or ↑ | ↑ | N or ↓ | ↓ |
Mineralization inhibitors | N | N | ↑ | N | N or ↓ | N |
N: normal; ↓: reduced; ↓↓: very reduced; ↑: elevated.
* Vitamin D deficiency is common and may be present in osteomalacia of any etiology or in osteoporosis.
¶ Parathyroid hormone may be mildly elevated in some disorders of renal phosphate wasting. Secondary hyperparathyroidism is common in X-linked hypophosphatemia, which can have a subtle presentation and remain undiagnosed until adulthood.
Δ Proximal (type 2) renal tubular acidosis may occur in isolation or in the setting of generalized proximal tubular dysfunction/Fanconi syndrome.Do you want to add Medilib to your home screen?