Nutritional Rickets: Your Nutritional Guide to Treatment

1. Nutritional rickets (see Table 1.16)
2. Vitamin D–deficiency rickets
3. Rare after addition of vitamin D to milk, except in the following populations:
4. Asian immigrants
5. Patients with dietary peculiarities
6. Premature infants
7. Patients with malabsorption (celiac sprue)
8. Patients receiving long-term parenteral nutrition
9. Decreased intestinal absorption of calcium and phosphate leads to secondary hyperparathyroidism.
10. Laboratory findings

11. Low-normal calcium level (maintained by high PTH level)

12. Low phosphate level (excreted because of the effect of PTH)

13. Increased alkaline phosphatase level

14. Low vitamin D level

15. Increased PTH level leads to higher bone absorption

16. Physical examination
17. Enlargement of the costochondral junction (rachitic rosary)
18. Bowing of the knees
19. Muscle hypotonia
20. Dental disease
21. Pathologic fractures (Looser zones: pseudofractures on the compression sides of bones)
22. Milkman’s fracture
23. Waddling gait
24. Radiographic findings

25. Physeal widening and cupping

26. Coxa vara
27. Codfish vertebrae
28. Retarded bone growth (defect in the hypertrophic zone, widened osteoid seams)
29. In affected children, height is commonly below the fifth percentile for age.
30. Treatment with vitamin D (1000–6000 IU daily
    based on weight) resolves most deformities.
31. Calcium-deficiency rickets ( Fig. 1.19)
32. Phosphate-deficiency rickets
33. Hereditary vitamin D–dependent rickets
34. Rare disorders with features similar to those of vitamin D–deficiency (nutritional) rickets, except that symptoms may be worse and patients may have total baldness

35. Type I: defect in renal 25(OH)D 1α-

hydroxylase, inhibiting conversion of inactive vitamin D to its active form

1. Autosomal recessive inheritance
2. Gene on chromosome 12q14
3. Type II: defect in an intracellular receptor for 1,25(OH)2D3
4. Familial hypophosphatemic rickets (vitamin D–resistant rickets or phosphate diabetes)
5. Most commonly encountered form of rickets
6. X-linked dominant inheritance
   
   
   FIG. 1.19 Nutritional calcium deficiency. From Netter FH: CIBA collection of medical illustrations, vol 8: Musculoskeletal system, part I: Anatomy, physiology and developmental disorders, Basel, Switzerland, 1987, CIBA, p 184.
7. Impaired renal tubular reabsorption of phosphate
8. Normal GFR with an impaired vitamin D3 response
9. Normal serum calcium, low serum phosphorus and 1, (OH)2D3, and high serum alkaline phosphatase levels
10. Treatment:
11. First line treatment with burosumab (anti-FGF23 monoclonal antibody)
12. Second line elemental phosphate (1–2 g/day plus vitamin D 0.5–1 µg/day)
13. Hypophosphatasia
14. Autosomal recessive
15. Error in the tissue-nonspecific isoenzyme of alkaline phosphatase
16. Leads to low levels of alkaline phosphatase, which is required for
    synthesis of inorganic phosphate (Pi) and important in bone matrix formation
17. Features are similar to those of rickets.
18. Increased urinary phosphoethanolamine is diagnostic.
19. Treatment may include phosphate therapy. Table 1.15 Laboratory Findings and Clinical Data Regarding Patients Changes in Level or Concentration --- Disorder Serum Serum Alka Calcium Phosphastase Phos Hypopara-thyroidism | ↓
    | ↑
    | Non Pseudohypoparathyroidism | ↓
    | ↑
    | Non Renal osteodystrophy (high-turnover bone disease resulting from renal disease [secondary hyperparathyroidism]) | ↓ or
    none
    | ↑↑↑
    | ↑
    | |
    | ---|---|---|--- Renal osteodystrophy | ↑ or
    none
    | None or ↑
    | ↑ (low-turnover bone | | disease due to renal | | disease [aluminum | | toxicity]) | |
    ↓, Decreased; ↑, increased.

Table 1.16 Laboratory Findings and Clinical Data Regarding Patients Changes in Level or Concentration --- Disorder Serum Serum Alkaline PTH Calcium Phos phos Nutritional rickets: vitamin D deficiency | ↓ or

none
| ↓
| ↑
| ↑
| |
| |
| ---|---|---|---|---| Nutritional rickets: calcium deficiency | ↓ or
none
| ↓
| ↑
| ↑ Nutritional rickets: phosphate deficiency | None
| ↓
| ↑
| None Hereditary vitamin D–dependent rickets type I (pseudo–vitamin D deficiency) | ↓
| ↓
| ↑
| ↑ Hereditary vitamin D–dependent rickets type II [hereditary resistance to 1,25(OH) 2D] | ↓
| ↓
| ↑
| ↑ Hypophosphatemic rickets (also known as vitamin D–resistant rickets and phosphate diabetes; Albright syndrome is an example of a | None
| ↓↓↓
| ↑
| None hypophosphatemic syndrome) | |
| |
| ---|---|---|---|---| Hypophosphatasia | ↑
| ↑
| ↓↓↓
| None
↓, Decreased; ↑, increased; phos, phosphatase.

Table 1.17 Differential Diagnosis of Metabolic Bone Diseases Based Calcium Level --- Increased | Decreased Primary | Hypoparathyroidism Pseudohypoparathyr Renal osteodystrophy (high-turnover bo

disease) Nutritional rickets: vi
D deficiency Nutritional rickets: ca
deficiency Hereditary vitamin D
dependent rickets (types I and II)
Malignancy with bon metastasis
Malignancy without metastasis
Multiple myeloma Lymphoma Hyperthyroidism Vitamin D intoxicatio Sarcoidosis
Milk-alkali syndrome Severe generalized
immobilization hyperparathyroidism Hyperthyroidism Vitamin D intoxication Malignancy without bony metastasis Malignancy with bony metastasis Multiple myeloma Lymphoma Sarcoidosis Milk-alkali syndrome Severe generalized immobilization Multiple endocrine neoplasias Addison disease Steroid administration Peptic ulcer disease Hypophosphatasia Pseudohypoparathyroidism Renal osteodystrophy Nutritional rickets: vitamin D deficiency Nutritional rickets: calcium deficiency Hereditary vitamin D– dependent rickets (types I and II)