2012 July » Easy Pediatrics

Introduction to Hypocalcemia

Jul 312012

Hypocalcemia is a laboratory and clinical abnormality that is observed with relative frequency, especially in neonatal pediatric patients.

Definition

Hypocalcemia is defined as a total serum calcium concentration of less than 2.1 mmol/L (8.5 mg/dL) in children, less than 2 mmol/L (8 mg/dL) in term neonates, and less than 1.75 mmol/L (7 mg/dL) in preterm neonates.

Hypocalcaemia is one of the commonest disorders of mineral metabolism seen in children and can be a consequence of several different aetiologies. These include a failure of secretion or action of parathyroid hormone, disorders of vitamin D metabolism and abnormal function of the calcium sensing receptor.

Normal Calcium Metabolism

Calcium is the most abundant mineral in the body. Of the body’s total calcium, 99% is in bone, and serum levels constitute less than 1%.Various factors regulate the homeostasis of calcium and maintain serum calcium within a narrow range. These include parathormone (PTH), vitamin D, hepatic and renal function (for conversion of vitamin D to active metabolites), and serum phosphate and magnesium levels.

Although total serum calcium levels are often measured and reported, ionized calcium is the active and physiologically important component.

The concentration of calcium in the serum is critical to many important biologic functions, including the following:

Calcium messenger system by which extracellular messengers regulate cell function
Activation of several cellular enzyme cascades
Smooth muscle and myocardial contraction
Nerve impulse conduction
Secretory activity of exocrine glands.

Effects of Hypocalcemia on the Bodily Functions

Hypocalcemia manifests as central nervous system (CNS) irritability and poor muscular contractility. Low calcium levels decrease the threshold of excitation of neurons, causing them to have repetitive responses to a single stimulus. Because neuronal excitability occurs in sensory and motor nerves, hypocalcemia produces a wide range of peripheral and CNS effects, including paresthesias, tetany (ie, contraction of hands, arms, feet, larynx, bronchioles), seizures, and even psychiatric changes in children.

Causes

Overall, one of the most common causes of hypocalcemia is renal failure, which results in hypocalcemia because of inadequate 1-hydroxylation of 25-hydroxyvitamin D and hyperphosphatemia due to diminished glomerular filtration.

Although hypocalcemia is most commonly observed among neonates, it is frequently reported in older children and adolescents, especially in PICU settings.

Hypocalcemia in a Neonate

In the neonatal age hpocalcemia may be caused by:

Prematurity

Birth asphyxia

Maternal Diabetes mellitus Continue reading »

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An Overview of Nephrotic Syndrome

Nephrology No Responses »

Jul 312012

Pediatric Nephrotic syndrome is defined by the presence of:

nephrotic proteinuria > 1 g/m²/day,
hypoproteinemia - albumin usually < 25 g/l, based on protein loss to urine,
hypercholesterolemia - based on increased lipoprotein synthesis (caused by hypoproteinemia),
edema - based on increased naturism resorption in tubules.

Nephrotic syndrome is a constellation of clinical findings that is the result of massive renal losses of protein. Thus, nephrotic syndrome is not a disease itself, but the manifestation of many different glomerular diseases.

Minimal Change Disease

Minimal Change Disease (also known as lipoid nephrosis) is a disease of thekidney that causes nephrotic syndrome and usually affects children (peak incidence at 2–3 years of age).

Pathophysiology

Nephrotic syndrome is a nonspecific disorder in which thekidneys are damaged, causing them to leak large amounts of protein from the blood into the urine.

Kidneys affected by nephrotic syndrome have small pores in the podocytes, large enough to permit proteinuria (and subsequently hypoalbuminemia, because some of the protein albumin has gone from the blood to the urine.

NS is believed to have an immune pathogenesis. Evidence of the immune-mediated nature of NS is demonstrated by the fact that immunosuppressive agents, such as corticosteroids and alkylating agents, can result in remission of nephrotic syndrome.

Pathology of Edema in Nephrotic Syndrome

The classical explanation for edema formation is a decrease in plasma oncotic pressure, as a consequence of low serum albumin levels, causing an extravasation of plasma water into the interstitial space. The resulting contraction in plasma volume (PV) leads to stimulation of the renin-angiotensin-aldosterone axis and antidiuretic hormone. The resultant retention of sodium and water by the renal tubules contributes to the extension and maintenance of edema.

A more recent theory of edema formation posits that massive proteinuria leads to tubulointerstitial inflammation and release of local vasoconstrictors and inhibition of vasodilation. This leads to a reduction in single-nephron glomerular filtration rate and sodium and water retention.

Thrombosis

Patients with nephrotic syndrome are at increased risk for thrombosis.

Various factors play a role in the increased incidence of thrombosis. Abnormalities described in INS include the following:

Increased platelet activation and aggregation
Elevation in levels of factors V, VII, VIII, and XIII and fibrinogen Continue reading »

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Managing Acute Abdominal Pain in Children

Gastroenterology No Responses »

Jul 312012

Abdominal pain is one of the most common reasons for a parent to bring his or her child to medical attention. Evaluation of a “stomach ache” can challenge both parents and the physician.

Possible causes for a child’s abdominal pain range from trivial to life-threatening, with little difference in the child’s complaints. Fortunately, abdominal pain in a child usually improves quickly. Each parent or caregiver faces the difficulty deciding whether a complaint needs emergency care or not.

Abdominal pain is a common problem in children. Although most children with acute abdominal pain have self-limited conditions, the pain may herald a surgical or medical emergency.

Causes to be kept in Mind

Although many cases of acute abdominal pain are benign, some require rapid diagnosis and treatment to minimize morbidity. Numerous disorders can cause abdominal pain. The most common medical cause is gastroenteritis, and the most common surgical cause is appendicitis.

In the acute surgical abdomen, pain generally precedes vomiting, while the reverse is true in medical conditions. Diarrhea often is associated with gastroenteritis or food poisoning. Appendicitis should be suspected in any child with pain in the right lower quadrant. Signs that suggest an acute surgical abdomen include involuntary guarding or rigidity, marked abdominal distention, marked abdominal tenderness, and rebound abdominal tenderness.

The list that should be in mind while evaluating a child with abdominal is is as follows:

Medical causes

Diabetic ketoacidosis
Inflammatory bowel disease
Acute adrenal failure
Gastroenteritis
Food Poisioning
Urinary tract infection
Hepatitis
Sickle cell crisis
Henoch-Schönlein purpura

Surgical Causes

Acute appendicitis
Bowel obstruction
Intussusception/ volvulus
Testicular torsion
Meckel’s diverticulum

Others

Infantile colic
Functional pain

History and Physical Examination

In a child presenting with acute abdominal pain a complete history and detailed physical examination is important to reach a proper diagnosis and then appropriate Continue reading »

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