Hypercalcemia and related disorders Flashcards
What is hypercalcemia defined as?
Plasma or serum [Ca(^{2+})] > 11 mg/dL or 1 mg/dL above the normal range
Which organs can be affected by hypercalcemia?
- Kidney
- Heart
- Brain
- Peripheral nerves
- Gut
What condition is considered a pseudohypercalcemia?
High adjusted or corrected total serum [Ca(^{2+})] in an individual with elevated serum albumin concentration
When is true hypercalcemia considered?
When serum ionized [Ca(^{2+})] is elevated above normal
What are the four major groups of causes of hypercalcemia?
- Increased Ca(^{2+}) mobilization from the bone
- Increased absorption of Ca(^{2+}) from the gastrointestinal tract
- Decreased urinary excretion of Ca(^{2+})
- Medications
What is the most common cause of hypercalcemia?
Primary hyperparathyroidism (PHPT)
What is the prevalence of primary hyperparathyroidism in terms of gender?
More common in elderly women than men
What percentage of primary hyperparathyroidism cases are due to a single adenoma?
80–85%
What are the clinical presentations of primary hyperparathyroidism?
- Mild hypercalcemia (60–80%) with minimal or no symptoms
- Moderate hypercalcemia (20–25%) with nephrolithiasis
- Severe hypercalcemia (5–19%) with kidney disease, bone disease, or GI tract problems
What laboratory findings are common in primary hyperparathyroidism?
- Elevated serum PTH
- Hypercalcemia
- Hypophosphatemia
- Elevated alkaline phosphatase
- Hypercalciuria
- Elevated urinary cyclic adenosine monophosphate (cAMP)
What is the standard therapy for severe and symptomatic primary hyperparathyroidism?
Surgery
What is the specificity of the sestamibi scan for preoperative localization of parathyroid glands?
90%
What are the indications for surgery in asymptomatic primary hyperparathyroidism?
- Serum Ca(^{2+}) level > 1 mg/dL above normal
- Reduced bone mineral density (T-score < –2.5)
- Kidney issues (eGFR <60 mL/min or 24-h urine calcium >400 mg)
- Age <50 years
What specific bone condition is associated with primary hyperparathyroidism?
Osteitis fibrosa cystica
Fill in the blank: Hypercalcemia due to increased absorption of Ca(^{2+}) from the GI tract can be caused by _______.
Granulomatous diseases, Vitamin D intoxication, Milk-alkali syndrome
True or False: Hypercalcemia can be caused by medications other than thiazide diuretics.
True
What are some specific causes of hypercalcemia related to medications?
- Lithium
- Vitamin D
- Vitamin A
- Growth hormone
- Estrogens/antiestrogens
- Theophylline
- Immune checkpoint inhibitors
What role does primary hyperparathyroidism play in the general population?
It is the most underlying and leading cause of hypercalcemia
What laboratory tests are used to diagnose primary hyperparathyroidism?
Serum parathyroid hormone (PTH) and electrolytes
What is a common complication of severe hypercalcemia in primary hyperparathyroidism?
Nephrolithiasis (kidney stones)
Fill in the blank: The binding of Ca(^{2+}) to globulins increases due to elevated _______.
Globulin levels
What is the mechanism of hypercalcemia associated with familial hypercalcemic hypocalciuria?
Inactivating mutations of Ca(^{2+}) sensing receptor (CaSR)
What are the guidelines for monitoring patients with asymptomatic PHPT who do not undergo parathyroid surgery?
- Serum [Ca²⁺] annually. 2. Dual-energy x-ray absorptiometry every 1–2 yr (3 sites). 3. eGFR and creatinine annually.
If kidney stones are suspected, a 24-h biochemical stone profile and kidney imaging by x-ray, ultrasound, or CT is performed.
