Disorders of calcium metabolism

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Disorders of calcium metabolism
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Muscle cramps, tetany, osteoporosis, kidney stones, neurological symptoms
Complications	Cardiac arrhythmias, osteomalacia, nephrocalcinosis
Onset	Varies depending on the specific disorder
Duration	Chronic or acute
Types	N/A
Causes	Hypoparathyroidism, hyperparathyroidism, vitamin D deficiency, renal failure, malabsorption
Risks	Genetic predisposition, dietary factors, medications
Diagnosis	Serum calcium test, parathyroid hormone levels, vitamin D levels, bone density scan
Differential diagnosis	Hypocalcemia, hypercalcemia, osteoporosis, Paget's disease of bone
Prevention	N/A
Treatment	Calcium supplements, vitamin D therapy, bisphosphonates, parathyroidectomy
Medication	Calcitriol, calcium carbonate, alendronate
Prognosis	Varies; depends on underlying cause and treatment
Frequency	Common, especially in older adults
Deaths	N/A

Disorders of calcium metabolism are a group of medical conditions that affect the regulation of calcium levels in the body. Calcium is an essential mineral that plays a critical role in various physiological processes, including bone formation, muscle contraction, nerve function, and blood clotting. The balance of calcium in the body is tightly regulated by the parathyroid hormone (PTH), vitamin D, and the kidneys.

Calcium Homeostasis

Calcium homeostasis refers to the maintenance of a stable concentration of calcium ions in the blood and extracellular fluid. The normal serum calcium level is approximately 8.5 to 10.5 mg/dL. The regulation of calcium involves:

• Parathyroid Hormone (PTH): Secreted by the parathyroid glands, PTH increases blood calcium levels by stimulating osteoclasts to break down bone, increasing renal tubular reabsorption of calcium, and activating vitamin D.
• Vitamin D: Enhances intestinal absorption of calcium and phosphate.
• Calcitonin: Secreted by the thyroid gland, it lowers blood calcium levels by inhibiting osteoclast activity.

Types of Disorders

Hypercalcemia

Hypercalcemia is a condition characterized by an abnormally high level of calcium in the blood. Common causes include:

• Primary Hyperparathyroidism: Overactivity of one or more of the parathyroid glands.
• Malignancy: Certain cancers can cause hypercalcemia through bone metastasis or secretion of parathyroid hormone-related peptide (PTHrP).
• Vitamin D Toxicity: Excessive intake of vitamin D supplements.

Symptoms of hypercalcemia can include nausea, vomiting, constipation, polyuria, polydipsia, confusion, and in severe cases, cardiac arrhythmias.

Hypocalcemia

Hypocalcemia is defined as a low level of calcium in the blood. Causes include:

• Hypoparathyroidism: Reduced secretion of PTH.
• Vitamin D Deficiency: Due to inadequate dietary intake, lack of sunlight, or malabsorption.
• Chronic Kidney Disease: Impaired conversion of vitamin D to its active form.

Symptoms of hypocalcemia may include muscle cramps, tetany, seizures, and cardiac arrhythmias.

Diagnosis

The diagnosis of calcium metabolism disorders involves:

• Serum Calcium Measurement: Total and ionized calcium levels.
• PTH Levels: To assess parathyroid function.
• Vitamin D Levels: To evaluate vitamin D status.
• Renal Function Tests: To assess kidney function.

Treatment

Treatment of calcium metabolism disorders depends on the underlying cause:

• Hypercalcemia: May require hydration, diuretics, bisphosphonates, or calcitonin.
• Hypocalcemia: Treated with calcium supplements and vitamin D.

See also

• Calcium in biology
• Parathyroid hormone
• Vitamin D
• Bone metabolism