-IBIS-1.5.0-
tx
endocrine system
hyperparathyroidism
diagnoses

definition and etiology

definition: A generalized disorder resulting from excessive secretion of parathyroid hormone (PTH); it is usually characterized by hypercalcemia, hypophosphatemia, and abnormal bone metabolism. Nephrolithiasis and reduction of bone mass are common.

etiology: Etiology is unknown.
• Conditions that lower serum Ca such as renal insufficiency and intestinal malabsorption syndrome can cause increased secretion of PTH over long periods. This is termed secondary hypoparathyroidism. It can lead to hyperplasia of the glands and ultimately oversecretion of PTH causing hypercalcemia.
• Certain malignancies (parathyroid, also lung, kidney, liver) can secrete PTH-like substances and are detected by radioimmunoassay.
• Hypercalcemia (consistent Ca levels >12.5 mg/dl) causes nervous system, alimentary tract, and kidney disorders.
• Neuromuscular transmission is reduced (muscle weakness memory loss) from calcium-induced hypokalemia.

signs and symptoms

Usually asymptomatic: hypercalcemia is found through routine lab work.
• peptic and duodenal ulceration
• irritability and memory loss
• muscle weakness
• anorexia
• constipation
• high urine volume from high solute load

lab findings:

primary hyperparathyroidism:
• increased serum PTH
• increased serum Ca; may need repeat determinations; measure total protein and albumin to assess meaning of calcium levels
• decreased serum phosphate
• serum alk. phos. may be slightly increased or normal
• increased urine Ca and PO4
• polyuria with low specific gravity
• serum chloride increased

secondary hyperparathyroidism: labs reflecting underlying disease
• serum Ca low or normal
• serum phosphate increased
• increased PTH
• decreased chloride

course and prognosis

• Osteitis fibrosis cystica (von Recklinghausen's disease) can occur in advanced cases demonstrated radiographically by large cysts where resorbed bone is replaced by fibrous cysts.
• "Metastatic calcifications" from hypercalcemia causing deposition of calcium, can be found in the kidneys (esp. renal tubules), lungs, blood vessels, and stomach.

• Controlling stimulus for the oversecretion of PTH is obviously the first consideration. Parathyroid adenomas must be addressed. Renal disease must be considered.

differential diagnosis

• Parathyroid adenomas
• Renal disease


footnotes