Calcium deficiency with normal or low-normal vitamin D status
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Very low dietary calcium intake |
Calcium malabsorption (similar causes as vitamin D malabsorption, see below) |
Vitamin D-related
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Severe vitamin D deficiency
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Low sunshine exposure and low dietary intake |
Malabsorption (e.g., after bariatric surgery, bowel resection, celiac disease, cholestatic liver disease, exocrine pancreatic insufficiency, inflammatory bowel disease) |
Increased renal loss of vitamin D and 25OHD (nephrotic syndrome) |
Increased catabolism: especially drug-induced or genetic mutations of CYP3A4 |
Impaired hepatic 25-hydroxylation: mostly due to genetic mutations of CYP2R1 (OMIM #600081) |
Impaired renal 1α-hydroxylation: chronic kidney disease (renal osteomalacia), or genetic (=1α-hydroxylase (CYP27B1) deficiency (OMIM #264700) |
Vitamin D resistant rickets
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Hereditary vitamin D-resistant rickets (VDR mutations) (OMIM #277440) |
Vitamin D-dependent rickets with normal VDR (hnRNP overexpression) (OMIM #600785) |
Phosphate related rickets/osteomalacia or Hypophosphatemic rickets/osteomalacia
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Gastrointestinal causes
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Poor nutritional intake (e.g., breastfed very low birth weight infants), |
Chronic diarrhea |
Excessive phosphate binders |
Renal phosphate wasting
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Tumor-induced (oncogenic) osteomalacia
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Fanconi syndrome (mostly HIV medications such as tenofovir)
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X-linked dominant hypophosphatemic rickets (PHEX mutations) (OMIM #307800)
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X-linked recessive hypophosphatemic rickets (CLCN5 mutations) (OMIM #300554)
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Autosomal dominant hypophosphatemic rickets (FGF23 mutations) (OMIM #193100)
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Autosomal recessive hypophosphatemic rickets type 1 (DMP1 mutations) (OMIM #241520), type 2 (ENPP1 mutations) (OMIM #613312)
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Hereditary hypophosphatemic rickets with hypercalciuria (SLC34A3) (OMIM #241530)
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Dent disease-1 (CLCN5 mutations) (OMIM #300009,)
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Dent disease-2 (OCRL mutations) (OMIM #300555)
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Rickets and osteomalacia related to inhibition of mineralization
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Metabolic acidosis (genetic or acquired) |
Metal related: aluminum toxicity (e.g., from antacids, dialysis fluid), fluorosis, iron, cadmium, strontium, etc. |
Hypophosphatasia (inorganic pyrophosphate accumulation) (OMIM #146300) |
Matrix abnormalities Type VI osteogenesis imperfecta (SERPINF1 mutations) (OMIM #613982) |
Fibrogenesis imperfecta ossium |
Axial osteomalacia |