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- See: Action of Parathyroid Hormone:

- Discussion:
    - most common cause of hypoparathyroidism is inadvertant damage or removal of the parathyroids during surgical removal of the thyroid;
    - in idiopathic cases, look for ectodermal changes, mental retardation, monilial infections, low Ca;
    - congenital hypoparathyroid & late onset hypoparathyroidism from other causes in adulthood  are rare conditions;
    - pseudohypoparathyroidism is another cause of this disorder;
           - end organ unresponsiveness to parathyroid hormone;
           - patients tend to be short and may have short metacarpals (index, ring, little);

- Laboratory Findings:
    - decreased plasma calcium; (see hypo Ca)
           - in the disorder of pseudopseudohypoparathyroidism, all of the clinical features of pseudoparathyroidism are present, but the serum 
                  calcium is normal;
    - increase in plasma phosphate;  (see hyperphosphatemia)
    - increase in renal tubualar reabsorption of phosphate
    - decrease in the number of bone remodeling centers;

- Radiographs:
    - eventhough in hypoparathyroidism there are fewer "bites" taken out of bone by the remodeling centers, this causes very few 
          abnormalities in bones in adults;
          - majority of these patients are treated w/ relatively high doses of Vit D to maintain their plasma Ca levels, which can, in itself, 
                 stimulate the bone remodely system;
    - subcutaneous calcifications may be present in pseudohypoparathyroidism, where as basal ganglia calcifications are seen in idiopathic 

- Treatment:
    - Ca supplements are generally used and it is important to add to diet at least 1 gm/day elemental calcium;
    - milk and cheese products (that are high in phospate content) should be avoided