Rickets arises due to decreased availability of phosphorus and calcium to mineralize the skeletal matrix, leading to growth plate disorganization and accumulation of undermineralized osteoid. This results in growth plate expansion, bone weakening, and skeletal deformities.
Primary causes include the following:
Ca | Phos | Alk phos | iPTH | 25-(OH)D | 1,25-(OH)2D | Urine Ca/ Cr | TRP | |
---|---|---|---|---|---|---|---|---|
Nutritional/insufficient sunlight | N or ↓ | ↓ | ↑ | ↑ | ↓ | ↑ | ↓ | ↑ |
Malabsorption | N or ↓ | ↓ | ↑ | ↑ | ↓ | ↑ | ↓ | ↑ |
Renal tubular defects | N or ↓ | ↓ | ↑ | ↑ | N | ↑ | ↑ | N or ↓ |
Altered vitamin D metabolism | N or ↓ | ↓ | ↑ | ↑ | ↓ | ↑ | ↓ | ↑ |
Genetic forms of rickets | ||||||||
X-linked, AD, and AR hypophosphatemic rickets | N | ↓ | ↑ | N or ↑ | N | N or ↑ | N or ↓ | ↓ |
1α-hydroxylase deficiency | ↓ | ↓ | ↑ | ↑ | N | ↓ | ↓ | ↑ |
Vitamin D receptor mutations (Vitamin D resistance) | ↓ | ↓ | ↑ | ↑ | N | ↑ | ↓ | ↑ |
Hereditary hypophosphatemic rickets with hypercalciuria | N or ↓ | ↓ | ↑ | ↑ | N | ↑ | ↑ | ↓ |
Hypophosphatasia | N or ↑ | N or ↑ | ↓ | N or ↓ | N | N or ↓ | N or ↑ | N |
Ca indicates calcium; Phos, phosphorus; Alk phos, alkaline phosphatase; iPTH, intact parathyroid hormone; 25-(OH)D, 25-vitamin D; 1,25-(OH)2D, 1,25-dihydroxyvitamin D; Ca/Cr, calcium/creatinine ratio; TRP, tubular reabsorption of phosphorus ([1− (U phos × P Cr/U Cr × S Phos)] × 100, normal 85–95%); N, normal; AD, autosomal dominant; AR, autosomal recessive.
There's more to see -- the rest of this topic is available only to subscribers.