Disorders of calcium metabolism

Disorders of Calcium Metabolism are a group of conditions that affect the balance and regulation of calcium in the body. Calcium is a vital mineral necessary for many bodily functions, including bone formation, muscle function, and nerve transmission. Abnormalities in calcium metabolism can lead to various clinical manifestations, ranging from asymptomatic laboratory findings to life-threatening conditions.

Etiology

Disorders of calcium metabolism can arise from several causes, including:

• Endocrine disorders, such as hyperparathyroidism and hypoparathyroidism, which affect the parathyroid glands' regulation of calcium.
• Vitamin D deficiency or disorders in vitamin D metabolism, impacting calcium absorption from the gut.
• Renal failure, leading to changes in calcium and phosphate handling.
• Genetic conditions, such as familial hypocalciuric hypercalcemia (FHH) and autosomal dominant hypocalcemia.

Pathophysiology

The regulation of calcium levels in the body is a complex process involving the bones, kidneys, and gastrointestinal tract, under the control of parathyroid hormone (PTH), vitamin D, and the calcitonin hormone. Disorders in any of these regulatory mechanisms can lead to disturbances in calcium metabolism.

Hypercalcemia

Hypercalcemia refers to elevated calcium levels in the blood. It can result from increased intestinal absorption, increased bone resorption, or decreased renal excretion of calcium. Common causes include hyperparathyroidism, malignancy, and vitamin D intoxication.

Hypocalcemia

Hypocalcemia is characterized by low levels of calcium in the blood. It can occur due to inadequate calcium intake, impaired calcium absorption, or excessive calcium loss. Causes include hypoparathyroidism, vitamin D deficiency, and renal disease.

Clinical Manifestations

Symptoms of calcium metabolism disorders vary widely and depend on the severity and rate of change of blood calcium levels.

Hypercalcemia

Symptoms of hypercalcemia may include polyuria, polydipsia, kidney stones, nausea, vomiting, constipation, muscle weakness, and cognitive disturbances.

Hypocalcemia

Hypocalcemia can present with neuromuscular irritability, including tetany (involuntary muscle contraction), seizures, prolonged QT interval on ECG, and psychiatric manifestations.

Diagnosis

Diagnosis of calcium metabolism disorders involves a thorough history, physical examination, and laboratory tests. Key laboratory tests include serum calcium, phosphate, magnesium, PTH, and vitamin D levels. Additional tests, such as urinary calcium excretion, may be necessary to determine the underlying cause.

Treatment

Treatment of disorders of calcium metabolism aims to correct the underlying cause and restore calcium balance.

Hypercalcemia

Treatment options for hypercalcemia may include hydration, bisphosphonates, calcitonin, and in severe cases, dialysis.

Hypocalcemia

Hypocalcemia treatment typically involves calcium supplementation and vitamin D therapy. In acute cases, intravenous calcium may be required.

Prevention

Preventive measures for disorders of calcium metabolism focus on adequate intake of calcium and vitamin D, regular exercise, and monitoring in individuals at risk.

Conclusion

Disorders of calcium metabolism encompass a wide range of conditions with diverse etiologies and clinical manifestations. Early recognition and appropriate management are crucial to prevent complications and improve outcomes.