Introduction:

Familial Hypocalciuric Hypercalcemia (FHH) is a rare genetic disorder that affects the body's ability to regulate calcium levels in the blood. It is characterized by persistently elevated levels of calcium, but paradoxically, individuals with FHH do not experience symptoms of hypercalcemia. This comprehensive article aims to provide a thorough understanding of Familial Hypocalciuric Hypercalcemia, including its causes, symptoms, diagnosis, treatment options, and management strategies.

Causes and Genetic Basis:

Familial Hypocalciuric Hypercalcemia is primarily caused by mutations in the calcium-sensing receptor (CaSR) gene. The CaSR gene provides instructions for making a protein that is involved in sensing and regulating calcium levels in the body. Mutations in this gene alter the function of the calcium-sensing receptor, leading to a malfunction in calcium regulation. FHH follows an autosomal dominant inheritance pattern, which means that a person needs to inherit only one copy of the mutated gene from either parent to develop the condition.

Symptoms and Clinical Features:

Familial Hypocalciuric Hypercalcemia is typically asymptomatic, meaning individuals with FHH do not experience symptoms related to high calcium levels. In some cases, mild symptoms such as fatigue, weakness, or frequent urination may be present, but they are usually not severe. Unlike other causes of hypercalcemia, FHH does not typically lead to complications such as kidney stones or bone loss.

Diagnosis of Familial Hypocalciuric Hypercalcemia:

The diagnosis of Familial Hypocalciuric Hypercalcemia involves:

• Blood tests: Blood tests are performed to measure calcium levels, parathyroid hormone (PTH) levels, and other related markers. In FHH, calcium levels are persistently elevated, while PTH levels may be normal or slightly elevated. Additionally, urine tests may reveal low levels of calcium excretion.
• Genetic testing: Genetic testing can confirm the presence of mutations in the CaSR gene associated with FHH, providing a definitive diagnosis. It can also help identify affected family members and guide appropriate management strategies.

Treatment and Management Options:

The management of Familial Hypocalciuric Hypercalcemia includes:

• Regular monitoring: Individuals with FHH require regular monitoring of calcium levels and related markers to ensure that levels remain within a safe range and to detect any potential complications.
• Lifestyle modifications: Although no specific dietary restrictions are required for FHH, it is generally recommended to maintain a balanced and healthy diet to support overall well-being.
• Medication adjustments: If individuals with FHH require treatment for other conditions, such as osteoporosis or kidney stones, medication adjustments may be necessary to account for their unique calcium metabolism.
• Genetic counseling: Genetic counseling may be recommended for individuals with FHH to assess the risk to other family members, provide information on the inheritance pattern, and discuss reproductive options.

Conclusion:

Familial Hypocalciuric Hypercalcemia is an inherited disorder characterized by elevated calcium levels in the blood without symptoms of hypercalcemia. By understanding its causes, symptoms, diagnosis, treatment options, and management strategies, individuals with FHH and healthcare providers can work together to ensure appropriate monitoring, minimize potential complications, and maintain optimal calcium balance.

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