Hypocalcemia: Causes, Symptoms, and Treatment

Hypocalcemia;

Introduction

Hypocalcemia, a condition characterized by low levels of calcium in the blood, can lead to various health complications if left untreated. This article aims to provide a comprehensive overview of hypocalcemia, including its causes, symptoms, and treatment options.

Causes of Hypocalcemia:

Causes of hypocalcemia fall into three main categories: PTH deficiency, high PTH, and other factors. Let’s delve into each category separately.

1. PTH Deficiency:

• Postsurgical: Most commonly seen after thyroid or parathyroid surgery, this accounts for about 75% of cases.
• Autoimmune: Autoantibodies attacking the parathyroid glands are a primary cause, notably in autoimmune polyglandular syndrome type I.
• Abnormal Parathyroid Gland Development: Linked with various genetic disorders such as DiGeorge syndrome or Charge Syndrome.
• Parathyroid Gland Destruction: Rarely caused by conditions like granulomatous diseases or certain medications.

2. High PTH Levels:

• Vitamin D Deficiency: Results in secondary hyperparathyroidism due to decreased calcium absorption.
• Chronic Kidney Disease (CKD): Impairs phosphate excretion and vitamin D metabolism, leading to elevated PTH levels.
• Pseudohypoparathyroidism (PHP): A genetic disorder resulting in resistance to PTH action.

3. Other Causes:

1. Pseudohypocalcemia: Caused by low albumin states, leading to falsely low serum calcium levels.
2. Acidosis/Alkalosis: pH levels affect calcium binding to albumin, influencing ionized calcium levels.
3. Acute Pancreatitis: Can induce hypocalcemia due to calcium precipitation.
4. Severe Sepsis/Critical Illness/Trauma: Various mechanisms, including impaired PTH secretion and magnesium dysregulation, can lead to hypocalcemia.
5. Hypomagnesemia/Hypermagnesemia: Both low and high serum magnesium levels can affect PTH secretion, leading to hypocalcemia.
6. Acute Hyperphosphatemia: Uncommon, but can cause hypocalcemia due to calcium phosphate deposition.
7. Drugs: Certain medications like bisphosphonates or chemotherapeutic agents can induce hypocalcemia.
8. Massive Blood Transfusion: Blood transfusion can decrease ionized calcium due to citrate binding.
9. Pregnancy: Hypocalcemia during pregnancy can result from various factors including poor diet or underlying diseases.
10. Osteoblastic Metastasis: Certain cancers, like prostate cancer, can cause hypocalcemia due to increased osteoblastic activity.
11. Nutritional Deficiencies: Inadequate intake of calcium-rich foods can result in hypocalcemia.
12. Vitamin D Deficiency: Vitamin D plays a crucial role in calcium absorption, and its deficiency can lead to low calcium levels.
13. Kidney Disorders: Conditions such as chronic kidney disease can impair the body’s ability to regulate calcium levels.
14. Hypoparathyroidism: Decreased secretion of parathyroid hormone (PTH) can cause a decrease in calcium levels.
15. Medications: Certain medications, including diuretics and antiepileptic drugs, can interfere with calcium metabolism, leading to hypocalcemia.

Symptoms of Hypocalcemia

1. Tingling Sensations: Numbness or tingling in the fingers, toes, or around the mouth.
2. Muscle Cramps: Painful spasms or cramps, particularly in the hands and feet.
3. Carpopedal Spasm (Trousseau’s Sign) : Reflects heightened neuromuscular excitability and manifests as hand spasms when a blood pressure cuff is inflated above systolic pressure.
4. Chvostek’s Sign: Another indication of increased neuromuscular excitability, elicited by tapping the facial nerve resulting in facial muscle contractions.
5. QTc Prolongation: Prolonged QT interval on an ECG, increasing the risk of ventricular tachycardia like torsades de pointes, which can be fatal.
6. Fatigue: Feelings of weakness or fatigue, often accompanied by muscle aches.
7. Irregular Heartbeat: Abnormal heart rhythms, palpitations, or chest pain.
8. Seizures: In severe cases, hypocalcemia can lead to seizures or convulsions.

Diagnosis :

1. Blood Tests: Measurement of calcium levels in the blood, along with tests for vitamin D and PTH.
2. Electrocardiogram (ECG): Assessment of heart function to detect any abnormalities associated with low calcium levels.
3. Bone Density Scan: Evaluation of bone health to assess calcium storage and turnover.

Treatment :

Treatment strategies for hypocalcemia depend on symptom severity, etiology, and patient condition. These approaches encompass:

1. Intravenous Calcium:

• Administered in severe cases or when QTC intervals are prolonged.
• Options include calcium gluconate or calcium chloride given as a short infusion followed by continuous infusion if needed.
• Calcium gluconate is preferred due to lower risk of tissue necrosis upon extravasation.
• Avoid alkaline or phosphorus-containing solutions to prevent calcium salt precipitation.

1. Oral Calcium:

• Suitable for mild symptoms.
• Calcium carbonate or calcium citrate are common choices.
• Aim for 1500 to 2000 mg of elemental calcium daily, divided into 2 to 3 doses to minimize gastrointestinal and renal losses.
• Consider vitamin D supplementation for better absorption, especially in scenarios with vitamin D deficiency.

1. Recombinant Human Parathyroid Hormone (rhPTH):

• Used for chronic hypoparathyroidism and select genetic conditions with low PTH levels.
• Limited by cost and availability, with potential long-term adverse effects.
• Other PTH preparations are under development for chronic hypocalcemia management.

Treatment of Hypocalcemia 2° to Systemic Disease:

• Postsurgical Hypoparathyroidism: Prophylactic calcium post-thyroidectomy or parathyroidectomy can prevent severe hypocalcemia, with close monitoring and gradual tapering of replacement calcium.
• Hypomagnesemia: Correct serum magnesium levels before addressing hypocalcemia.
• Vitamin D Deficiency: Replete vitamin D before correcting hypocalcemia.
• Chronic Kidney Disease (CKD): Address CKD-related hypocalcemia with activated vitamin D, such as calcitriol, and manage vitamin D deficiency with appropriate supplementation. Counsel patients on nephrolithiasis risk reduction strategies if indicated.

Summary:

Hypocalcemia can have serious implications for overall health and well-being, but with timely diagnosis and appropriate treatment, the condition can be effectively managed.

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