Hypocalcemia

 Hypocalcemia

Normal level of serum calcium; 8.5-10.5mg/dl

Hypocalcemia defines total serum calcium concentration less than 8.5mg/dl in children.

In term Neonates; <8.5mg/dl

In preterm Neonates; <7mg/dl

Function of Calcium

1. Calcium messanger system

Regulate cell function

2. Nerve impulse conduction

3. Smooth muscle and myocardial contraction

4. Activation of cellular enzyme

5. Secretory activity of exocrine glands

Etiology

1. Vitamin D deficiency

Due to;

Malabsorption

Malnutrition

Prolonged phenytoin therapy

Abnormal metabolism of vitamin D

Congenital rickets

2. Metabolic causes

Hypoparathyroidism

3. Increased calcium loss of from body 

Prolong fursemide therapy

Hypercalciuria

4. Others

1. Phototherapy

2. Infant fed with milk having high phosphate content

3. Exchange transfusion with citrate blood

4. Di George Syndrome; disorder caused by defect in chromosome 22

Pathophysiology

Due to etiological factor

Low level of calcium manifests as irritability of central nervous system and poor muscle contractility.

Produces Peripheral and CNS effect including; paraesthesia, tetany (contraction of hands, arms, feet, larynx, bronchioles, seizures, and may cause mental status changes in Children.

Clinical features

1. Early Neonatal hypocalcemia, occurs within 48-72 hours of birth, manifested by;

a. High pitch cry

b. Oedema

c. Vomiting

d. Abdominal distension

e. Periods of apnea

f. Intermittent cyanosis

2. Late Neonatal hypocalcemia

Occurs, 3-7days after birth, manifested include;

1. Muscular twitching

2. Tremors/ convulsion 

3. Carpopedal spasm (spasm of muscles of hand and feet)

4. Laryngospasm

5. Chvostek's sign is positive

Light taps on cheek stimulates facial nerve and lead to abnormal spasm of facial muscles.

6. Trousseau's sign is positive 

Blood pressure cuff placed around the arm and inflated to pressure and held in place for 3 minutes. It will occlude the brachial artery.

In absence of blood flow, patient with hypocalcemia; induce spasm of muscles of hand and forearm.

Wrist and metacarpophalangeal joint flexes and fingers adduct.

Diagnostic Evaluation

1. History of mother, newnates born with to diabetic mother have hypocalcemia.

2. Preterm infants develop hypocalcemia easily.

3. Estimation of Gestational Age of neonates.

4. Blood investigation;

a. Serum calcium

b. Serum phosphate

c. Serum alkaline phosphatase

5. Hormone assay; parathyroid hormone estimation 

6. Skiagram of hands; show sign of tetany.

Management

1. Calcium therapy

20% Calcium gluconate administered.

Dose of 2ml/kg, intravenous given to control seizure.

Later on, 5ml/kg/day of 10% calcium gluconate is administered.

Note- 

IV infusion of calcium can cause severe tissue necrosis resulting in contractures.

Carefully assess integrity of IV site before administering of calcium.

2. Oral calcium therapy

3. Administer magnesium to correct any hypomagnesemia because hypocalcemia doesn't respond until low magnesium level corrected.

4. When magnesium is too low; insufficient parathyroid hormone produced and blood calcium level reduced (hypocalcemia).

Prevention

1. Diet

Diet high in calcium and low phosphorus.

2. Infant susceptible to hypoglycemia

Calcium glutamate dose 1ml/kg IV, administered every 4 hours.

3. Calcium and phosphate oral preparation (in 2:1 ratio); given to neonates.