Pathophysiology
1) abnormally high serum calcium Causes – 2) malignancy-related 3) parathyroid-related 4) vitamin D-related 5) high bone turnover-related 6) renal failure-related
Signs and Symptoms
1) weakness and fatigue 2) headaches 3) constipation 4) anorexia 5) vomiting 6) abdominal pain 7) depression 8) confusion and coma 9) pruritis 10) polyuria and polydipsia 11) metastatic soft tissue calcification 12) bone pain
Characteristic Test Findings
Laboratory – 1) decreased serum phosphorus 2) increased serum gastrin 3) abnormal levels of PTH (can be high or low, depending on cause 4) presence of parathormone-like substance (if caused by squamous cell carcinoma of lung) 5) calciuria Radiology – 6) calcification of heart valves, lungs, and blood vessels on plain films EKG – 7) shortened QT interval
Histology/Gross Pathology
calcium deposition in renal tubules, blood vessels, and alveolar septa of lung
Associated Conditions
increased incidence of – 1) pancreatitis 2) peptic ulcer disease 3) nephrolithiasis (kidney stones) 4) nephrocalcinosis 5) hypertension
Biochemistry
malignancy-related hypercalcemia caused by – 1) bone metastases 2) osteoclast activating factors 3) paraneoplastic release of parathormone-like substance
Treatment
1) hydration 2) forced diuresis (furosemide) 3) bisphosphonates such as pamidronate or zoledronate 4) calcitonin 5) mithramycin (largely replaced by bisphosphonates) 6) dialysis (in renal failure) 7) glucocorticoids (especially in bone metastases and vitamin D intoxication) 8) correction of underlying condition (stopping antacids or vitamin D intake)
Tips for USMLE
1) think moans, bones, stones, and groans (confusion, bone pain, kidney stones, abdominal pain) – this also applies to hyperparathyroidism 2) if question mentions a high serum calcium and a high serum PTH, think hyperparathyroidism
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