Disorders of Ca and Phosphate Regulations

1) Primary hyperparathyroidism

• increased plasma Ca (often asymptomatic),
• decreased plasma Phosphate
• demineralization & osteopenia
• parathyroid carcinoma - common cause, can occurs in MEN 1 & 2a
• increased PTH
• increased alkaline phosphatase

2) Secondary hyperparathyroidism due to chronic renal failure

• decreased plasma Ca
• increased plasma Phosphate (due to decreased phosphate excretion)
• osteomalacia in adults
• rickets in children
• commonly caused by chronic renal failure & decreased Ca absorption, that stimulates PTH
• increased PTH
• increased alkaline phosphatase

3) Primary hypoparathyroidism

• decreased plasma Ca
• increased plasma Phosphate
• caused by DiGeorge syndrome, idiopathic, accidental removal during thyroidectomy
• irritability, anxiety, tetany, intracranial & lens calcification

4) Secondary hypoparathyroidism

• in excess of vitamin D--> osteoporosis
• increased plasma Ca
• increased plasma Phosphate

5) Hypercalcemia

• malignancy
• intoxication
• sarcoidosis
• hyperparathyroidism
• alkali-syndrome
• Paget disease

6) Pseudohypoparathyroidism

• aut-dom disease
• kidney are unresponsive to circulating PTH
• short stature
• shortened 4 & 5 carpals and metacarpals
• obesity
• developmental delay
• dental hypoplasia
• soft tissue calcification
• decreased plasma Ca
• increased plasma Phosphate
• increased PTH