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What is Hypocalcemia:Nursing Case Study

Thursday, 6 March 2014

Hypocalcemia
Hypocalcemia is commonly seen in neonates, particularly those of low birth weights below 1,500 g, premature neonates (less than 32 weeks' gestation), neonates of mothers with diabetes, and those who experienced birth asphyxia. Neonatal hypocalcemia can be broken into two categories:

■ Early onset in the first 48 to 72 hours after birth is typically asymptomatic and possibly not requiring treatment because it usually remits spontaneously within the 72 hours and doesn't recur.

■ Late onset occurs 3 to 7 days after birth, usually with clinical and laboratory evidence and requiring treatment.
Trousseau sign of latent tetany is a medical sign seen in patients with Hypocalcemia
Pathophysiology
Serum calcium represents only 1% of the total calcium in the body, but we rely on it to regulate certain cell functions and trigger several enzyme cascades in cells, stimulate secretions from the exocrine glands, conduct nerve impulses, and facilitate the contraction of smooth and cardiac muscles. Of the 1% calcium in the blood, only 50% is unbound to other proteins or minerals and, therefore, free to carry out all the actions cited above. The free calcium is called "ionized," and laboratory testing reveals its normal range to be 4 to 5 mg/dl out of a total serum calcium range of 8.5 to 10.5 mg/dl. These ranges are maintained by the interactions of several other electrolytes and hormones, including parathyroid hormone (PTH), vitamin D, phosphate, and magnesium as well as the efficiency of the kidneys and liver in metabolizing these chemicals.

When calcium levels are low, the excitability threshold of neurons decreases, resulting in sensory and motor nerve effects and central nervous system effects. While the nerves are overstimulated, the muscles can't respond promptly because the lack of calcium ions slows the release of acetylcholine at the neuromuscular junction. Eventually, the neuronal excitability overcomes the inhibition of muscle contraction, and tetany of the extremities, larynx, and bronchioles results. The cardiac muscle commonly remains inhibited and continues to contract poorly.

Complications
■ Adverse effects of I.V. calcium administration
■ Severe tissue necrosis if extravasation of peripheral line
■ Liver necrosis if accidentally misplaced into portal vein via umbilical vein
■ Intestinal necrosis if rapidly infused through an umbilical artery
■ Arterial spasm if rapidly infused through an arterial line
■ Brain damage from seizures and other insults triggered by very low calcium levels
■ Cardiac arrhythmias and decreased cardiac output from very low or very high calcium levels
■ Severe laryngospasm with airway obstruction

Assessment (only potential abnormalities listed)
Nursing history by functional health pattern
Health perception and management

■ Preterm delivery, small for gestational age, or low birth weight (neonate hasn't accumulated calcium)
■ Abnormal presentation, breech delivery, maternal hemorrhage, treatment with magnesium sulfate, birth by emergency cesarean section because of fetal distress, or trauma during delivery (such as use of forceps, vacuum extraction, gestational hypertension)
■ Phototherapy

Nutrition and metabolism
■ Use of formula with high phosphorus content and low calcium‑phosphorus ratio
■ Use of cow's milk (high phosphate level)
■ Use of formula with butter fat (may cause calcium malabsorption)
■ Illnesses, such as sepsis, hypoglycemia, cerebral injury, and respiratory distress syndrome (withholding food and water because of illness prevents oral intake of calcium)

Elimination
■ Abdominal distention

Activity and exercise
■ Jitteriness
■ Edema
■ Apnea
■ Intermittent cyanosis

Physical examination
General appearance and nutrition
■ Healthy neonate or acutely ill

Mental status and behavior
■ Irritable
■ High‑pitched cry

Respiratory
■ Respiratory distress
■ Apnea
■ Stridor
■ Laryngospasm

Cardiovascular
■ Arrhythmias
■ Cyanosis
■ Signs of congenital heart disease

Gastrointestinal
■ Feeding intolerance or inability to feed
■ Vomiting
■ Abdominal distension

Neurologic
■ Jittery movements
■ Hypertonicity
■ Localized twitching
■ Seizures
■ Tremulousness
■ Chvostek's sign
■ Carpopedal spasm
■ Trousseau's sign
■ Lethargy

Musculoskeletal
■ Initial weakness and decreased movement

Renal and urinary
■ Edema
■ Decreased urine output, concentrated urine

Diagnostic studies
■ Serum total calcium level of less than 7 mg/dl in a premature neonate or less than 8 mg/dl in a full-term neonate defines hypocalcemia.
■ Serum ionized calcium level of less than 4 mg/dl confirms hypocalcemia.
■ Serum albumin shows decreased level associated with decreased total calcium and abnormal pH.
■ Serum phosphorus level increased to 8 mg/dl or more with renal failure and hypoparathyroidism; decreased level with vitamin D abnormalities and rickets; type of abnormality helps establish etiology of hypocalcemia.
■ Serum magnesium level of less than 0.46 mmol/L causes hypocalcemia.
■ Serum electrolytes and serum glucose levels with decreased sodium and decreased glucose may cause neonatal seizures and irritability; decreased bicarbonate and acidosis may contribute to renal tubular acidosis.
■ PTH level decreases or increases in relation to magnesium and calcium levels indicate the possible cause of hypocalcemia.
■ Vitamin D metabolite levels with values in relation to PTH indicates possible cause of hypocalcemia.
■ Serum alkaline phosphatase is usually elevated with rickets.
■ Urinalysis for calcium, magnesium, phosphorus, glucose, protein, pH, and creatinine levels, including urine calcium-creatinine ratio, reveal abnormalities that may indicate renal tubular defects, renal failure, or calcium inappropriate excretion.
■ Chest X-ray checks for thymic shadow, which is absent in DiGeorge syndrome.
■ Ankle and wrist radiography shows evidence of rickets.
■ Electrocardiography reveals a characteristic prolonged QT and ST segment and T-wave abnormalities.
■ Maternal and family screening for familial forms of hypocalcemia reveal rare disorders (only tested when suspected).


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