hypocalcemia



OVERVIEW

Definition

Hypocalcemia is defined as a total blood calcium level of ≤2.13 mmol/L (8.5 mg/dl) in the presence of normal blood albumin concentrations.

Symptoms of hypocalcemia of varying degrees usually occur when blood calcium is ≤1.88 mmol/L and serum calcium is ≤0.95 mmol/L.

Calcium and phosphorus metabolism in the body is mainly regulated by three hormones: parathyroid hormone (PTH), 1,25-dihydroxyvitamin D3 (osteotriol) and calcitonin.

The main physiological roles of calcium ions include osteogenesis (which plays a supportive and protective role), coagulation, regulation of cellular function, regulation of enzyme activity, maintenance of neuromuscular excitability (when the concentration of calcium ions decreases, neuromuscular excitability increases, which can lead to convulsions), and inhibition of inflammation and edema.

Classification

According to the rate of decrease of blood calcium, it can be divided into: acute hypocalcemia and chronic hypocalcemia.

Causes

Causes

Acute hypocalcemia

Acute hemorrhagic necrotizing pancreatitis: fatty acids are released from the pancreas due to inflammation and necrosis, and the combination of fatty acids and calcium leads to hypocalcemia.

Rhabdomyolysis: The damage and lysis of the rhabdomyosin, the disruption of the cell membrane and the release of myocyte contents into the extracellular fluid and the blood circulation, resulting in the disturbance of the internal environment, acute kidney injury, etc., leading to hypocalcemia.

Chronic hypocalcemia

Decreased production of parathyroid hormone (PTH) is caused by accidental removal of parathyroid glands during parathyroid or thyroid surgery, damage to the parathyroid glands by radiation therapy to the neck, as well as developmental disorders or damage to the parathyroid glands due to genetic factors or autoimmunity.

Hypocalcemia results from complete or incomplete loss of the PTH target cell response to PTH due to defective PTH receptors or post-receptors caused by pseudohypoparathyroidism.

Patients suffering from severe hypomagnesemia may temporarily inhibit PTH secretion, while the responsiveness of target organs to PTH is delayed, and intestinal absorption of calcium and renal tubular reabsorption of calcium are impaired, leading to a decrease in blood calcium concentration.

Vitamin D can promote the absorption of calcium in the human body. Vitamin D metabolism disorder can lead to hypocalcemia, and the common causes are as follows.

Vitamin D deficiency: insufficient sunlight exposure, malnutrition and malabsorption.

Impaired intestinal absorption: suffering from small bowel disease, pancreatic and biliary tract disease or having undergone partial gastrectomy.

Vitamin D hydroxylation disorders: Reduced active vitamin D due to vitamin D hydroxylation disorders, causing decreased intestinal calcium absorption and increased urinary calcium, resulting in lower blood calcium. Most commonly seen in liver failure, renal failure, hereditary 1α-hydroxylase deficiency, etc.

Accelerated vitamin D catabolism: long-term application of antiepileptic drugs (e.g., phenytoin sodium, phenobarbital) can make the body’s need for vitamin D increase.

Hypocalcemia can occur in the advanced stage of chronic renal failure, which is associated with vitamin D hydroxylation disorders, high blood phosphorus, and active vitamin D insufficiency.

Symptoms

Main Symptoms

Neuromuscular symptoms

Twitching of the hands and feet is one of the typical manifestations of hypocalcemia, which early manifests as numbness in the fingers and around the mouth.

Severe hypocalcemia can also lead to bronchospasm, seizures, etc. It can also be accompanied by autonomic dysfunction, such as sweating, vocal spasm and tracheal respiratory muscle spasm.

Some patients may have psychiatric symptoms, such as restlessness, depression and agitation.

Dental and skin symptoms

Dental symptoms: underdevelopment of tooth enamel, delayed teething, caries and even missing teeth.

Skin symptoms: rough skin with cracks, sparse body hair that is easy to fall off and brittle finger (toe) nails.

Eye symptoms

Cataract is more common in patients with chronic hypocalcemia, and its severity is related to the duration of hypocalcemia and blood calcium level.

The main manifestations are decreased visual acuity, blurred vision, visual field defects, and double vision.

Other symptoms

Cardiovascular system symptoms: patients may experience bradycardia or arrhythmia.

Skeletal changes: patients with long duration and severe disease may have skeletal pain, which is more common in the lower back and hip.

Consultation

Department of Medicine

Endocrinology

When symptoms such as numbness and tingling in the fingers or around the mouth, muscle spasms in the hands, feet and face, and brittle and easily broken nails occur, timely consultation is recommended.

Pediatrics

If an infant or young child has irritability, delayed closure of fontanel, square head, chicken chest, O-shaped or X-shaped legs, etc., it is recommended to consult the doctor promptly.

Emergency Medicine

Immediate medical attention is recommended for symptoms such as tetany (spasms of the hands and feet in the form of bowing, fingers forming an eagle’s claw, straightening of the ankle joints of the feet, and simultaneous downward bending of the toes), apnea, and loss of consciousness.

Preparation for medical treatment

Preparing for your visit: registering, preparing your documents, and frequently asked questions.

Tips for the doctor

For the convenience of the doctor’s examination, women should try not to wear dresses.

It is recommended to record the date of onset of symptoms and the duration of each attack for the doctor’s reference.

Preparation Checklist for Doctor’s Visit

Pay particular attention to the time of onset of symptoms, special manifestations, etc.

Is there any numbness or tingling in the ends of the fingers or around the mouth, muscle spasms in the hands, feet and face?

Are there premature tooth loss, brittle nails, dry skin?

Any allergies to medications, foods or other substances?

Are there any diseases such as hypoparathyroidism or chronic renal failure?

Any previous neck surgery or thyroidectomy, parathyroidectomy, etc.?

Test results in the last six months, which can be brought to the doctor’s office

Laboratory tests: blood electrolytes, urine electrolytes, blood parathyroid hormone (PTH) test, blood routine, renal function, liver function, thyroid function

Imaging tests: cardiac ultrasound, abdominal ultrasound, cranial CT, cranial magnetic resonance imaging, abdominal CT, bone density

Other tests: electrocardiogram

Medication in the last 3 months, if available, bring the box or package with you to the doctor’s office

Calcium supplements: calcium carbonate, calcium gluconate, calcium lactate

Vitamin D and its derivatives: osteotriol, alfacalcitol (1α-hydroxylated vitamin D3), vitamin D3 (cholecalciferol)

Diagnosis

Diagnosis is based on

Medical history

History of hypoparathyroidism, malnutrition, cirrhosis, renal failure, and hereditary 1α-hydroxylase deficiency.

History of medications such as phenytoin sodium and phenobarbital.

History of surgery such as neck surgery, thyroidectomy, parathyroidectomy, etc.

Clinical manifestations

Numbness and tingling of the fingertips or perioral area, muscle spasms of the hands, feet and face, rough skin, brittle and easily broken nails, etc. may occur.

In severe cases, convulsions of hands and feet, seizures, apnea and loss of consciousness may occur.

Positive Facial Nerve Percussion Test: Finger percussion 2~3 cm in front of the ear can cause twitching of the corner of the mouth or nose on the same side, and in severe cases, twitching of the muscles on the same side of the face, but the specificity of this test is low.

Positive arm compression test: stopping venous return in the upper arm by applying localized pressure to the arm for 2-3 minutes can cause wrist spasms or eagle claw-like hands, and this test is more specific than the facial nerve percussion test.

Laboratory tests

Mainly, serum calcium and phosphorus plasma concentrations are measured.

Multiple measurements of serum calcium <2.13 mmol/L, or serum calcium ion <0.95 mol/L can be diagnosed as hypocalcemia.

Serum phosphorus is increased in most patients and partially normal.

It helps to distinguish whether it is due to hypoparathyroidism.

A decrease in urinary calcium and a decrease in urinary phosphorus excretion are present.

Laboratory tests such as urine routine, renal function, blood magnesium, amylase, blood alkaline phosphatase, vitamin D metabolites, thyroid function, and autoimmune antibodies may be performed as appropriate.

They are mainly used for differential diagnosis and to clarify the etiology of hypocalcemia.

Electrocardiogram

Hypocalcemia can elevate myocardial excitability and conduction. Electrocardiogram mostly shows Q-T interval and ST segment prolongation, and low or inverted T wave.

Precautions: The chest leads of ECG will be placed on the chest, and the examination should be performed quietly and lying down, do not take deep breaths or change the position.

Differential Diagnosis

Hypocalcemia can be clearly diagnosed by measuring blood electrolytes, and usually no differential is needed, focusing on finding the cause of hypocalcemia.

Treatment

The main goal of treatment for hypocalcemia is to control symptoms and normalize or near-normalize serum calcium.

General treatment

Active treatment of the primary disease: e.g. hypoparathyroidism, malnutrition, cirrhosis, renal failure.

Nutritional support: eat more food rich in calcium and vitamin D, such as sea fish, eggs, milk and dairy products.

Adjustment of medication: If anti-epileptic drugs (e.g. phenytoin sodium, phenobarbital, etc.) have been applied for a long period of time, the medication can be adjusted according to the doctor’s requirements.

Medication

Acute hypocalcemia

When the patient has sudden tetany, laryngospasm, seizures, convulsions, etc., immediate rescue treatment is needed.

Generally, it is necessary to give intravenous injection of 10% calcium gluconate 10-20 ml, the injection time is suitable for 10-15 minutes, and if necessary, repeat the injection after 1-2 hours, and at the same time give oral calcium and vitamin D preparations.

If the convulsions are severe and difficult to relieve, 10% calcium gluconate can be continuously injected intravenously, and the serum calcium level can be regularly monitored during the medication period, so that it can be maintained at >2.0mmol/L to avoid hypercalcemia.

If convulsions and spasms are severe, intramuscular diazepam or phenytoin sodium can be injected to rapidly control symptoms.

Chronic hypocalcemia

Long-term calcium supplements are required under medical supervision. Commonly used calcium supplements include calcium carbonate, calcium gluconate, calcium lactate and calcium chloride.

In patients with mild or asymptomatic chronic hypocalcemia, blood calcium can be basically normalized and symptoms can be controlled with oral calcium therapy alone.

Vitamin D and its derivatives are often used in combination.

Commonly used drugs include osteotriol, alfacalcitol (1α-hydroxyvitamin D3), vitamin D3 (cholecalciferol), and vitamin D2 (ergocalciferol).

Adverse reactions such as constipation, diarrhea, persistent headache, loss of appetite, metallic taste in the mouth, nausea, vomiting, thirst, and fatigue may occur.

Blood and urine calcium levels should be rechecked regularly during the medication period and the dosage should be adjusted promptly to avoid vitamin D overdose toxicity and hypercalcemia.

For those with hypomagnesemia, magnesium preparations can be supplemented, such as potassium magnesium menthylate, magnesium sulfate and so on.

Generally, after the hypomagnesemia is corrected, the hypocalcemia may also improve.

Prognosis

Cure

For hypocalcemia caused by malnutrition, drugs, etc., it can usually be corrected after removing the cause.

For hypocalcemia caused by hypoparathyroidism, chronic renal failure, etc., the symptoms can be relieved or controlled with timely and standardized treatment, but long-term medication is often required.

Severe hypocalcemia that progresses rapidly has a high mortality rate if left untreated.

Hazards

Hypocalcemia may cause numbness in the fingers or around the mouth, muscle spasms in the hands, feet and face, dry skin, and brittle nails that are easy to break, which may affect normal life and work.

Severe hypocalcemia patients may suddenly take hold of the hands and feet, apnea, loss of consciousness, etc. If not treated in time, it may be life-threatening.

Long-term hypocalcemia patients are prone to complications such as hypocalcemic cataract, vitamin D deficiency rickets, osteochondrosis and osteoporosis.

Daily

Daily Management

Dietary management

Maintain a normal diet without picking and favoritism.

Eat more food containing more calcium and vitamin D, such as sea fish, eggs, milk and dairy products.

Life Management

In case of muscle spasms in hands and feet, etc., bed rest is recommended to prevent injuries from falls.

Participate in more outdoor exercise and sunshine.

Quit smoking and limit alcohol consumption.

Regularize your work routine and avoid over-exertion.

Avoid stress, anxiety, anger, depression and other negative emotions.

Disease monitoring

Follow your doctor’s instructions and take regular tests on serum electrolytes, parathyroid hormone (PTH), and urine electrolytes, etc., in order to keep abreast of changes in your condition and adjust your medication.

Prevention

Ensure a balanced diet, diversified food types, light diet (less salt and oil), and moderate intake of dairy products.

Regular outdoor activities, more sunshine.

When using drugs such as phenytoin sodium and phenobarbital for a long period of time, attention should be paid to monitoring blood calcium and adjusting the medication or supplementing calcium as prescribed by the doctor.

Actively treat related diseases, such as chronic diarrhea and chronic renal failure.