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Vitamin-D Deficient Rickets

- See: Rickets:

- Discussion:
    - this is the classic form of the disease;
    - it usually results from a deficiency in dietary intake of vitamin D, often coupled with inadequate exposure to sunlight;
    - reduced vitamin-D intake causes a diminution in the absorption of calcium from the GI tract;
    - insufficient absorption results in a diminished serum calcium level, which subsequently causes a secondary hyperparathyroidism and resultant
            increase of the serum Ca concentration to low normal and a phosphate diuresis;
    - combination of a reduced amount of mineral (both ionized Ca & phos) & secondary hyperparathyroidism is presumed to be principal factor
            responsible for pathological changes in epiphyseal plates (in rickets) & bones & resultant alterations in x-rays images;
    - chelators in the diet:
           - see: GI and biliary causes of rickets
           - major dietary inclusions that can bind calcium and render it unabsorbable in the ionized state are phytate (from some coarse cereals), oxalate (present
                    principally in spinach), & excess of phosphate;
    - phosphorus deficiency:
           - can occur with the introduction into diet of beryllium (as an industrial toxic material) or, much more commonly, aluminum (present as Al(OH) in
                    many antacid preparations);
    - infantile nutritional rickets:
most common in african americans who are breast fed for more than 6 months and who do not receive vitamin D;

- Clinical Findings:

    - children with this disorder usually show the abnormality by age of one year or, in florid cases, even earlier.
    - they may display severe weakness, inability to walk, and remarkable deformities of the skeleton (genu varum and swollen wrists);
    - adults, in contrast, have few localizing symptoms or findings;
    - they may complain of malaise, easy fatigability, bone pain & tenderness, weakness, or a combination of these symptoms;
    - physical findings in the adult are sparse but may include a Trendelenburg gait and tenderness over osseous prominences;
    - great concern, particularly in dealing w/ elderly pt, is that osteopenia or fracture may be attributed to osteoporosis when, in fact, it represents
             nutritional osteomalacia;

- Radiographs:

- Labs:
    - hypophosphatemia may be present due to phosphate diuresis (may be normal in some patients);
    - hypocalcemia may be present (or may be low normal);
    - alkaline phosphatase is generally elevated;
    - BUN and Cr are normal