2010 October » Easy Pediatrics

Gonadal and Germ Cell Neoplasms in Children

Oct 262010

Malignant germ cell tumors (GCTs) and gonadal tumors are rare, with an incidence of 12 cases per million persons <20 yr of age. Most malignant tumors of the gonads in children are GCTs. The incidence varies according to age and sex.

Sacrococcygeal tumors occur predominantly in infant girls.

Testicular GCTs occur predominantly before age 4 yr and after puberty. Testicular GCTs occur much more often in whites than in blacks, whereas ovarian GCTs have a slight predominance in blacks.

Klinefelter syndrome is associated with an increased risk of mediastinal GCTs;

Down syndrome, undescended testes, infertility, testicular atrophy and inguinal hernias are associated with an increased risk of testicular cancer.

Clinical Manifestations And Diagnosis

The clinical presentation of germ cell neoplasms depends on location. Ovarian tumors often are quite large by the time they are diagnosed. Extragonadal GCTs occur in the midline, including the suprasellar region, pineal region, neck, mediastinum, and retroperitoneal and sacrococcygeal areas. Symptoms relate to mass effect, but the intracranial GCTs often present with anterior and posterior pituitary deficits.

The serum ?-fetoprotein (AFP) level is elevated with endodermal sinus tumors and may be minimally elevated with teratomas. Infants have higher levels of AFP, which fall to normal adult levels by about 8 mo; therefore, high AFP levels must be interpreted with caution in this age group. Elevation of the ? subunit of human chorionic gonadotropin (?-hCG) is seen with Continue reading »

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Hookworms Infection in Children

Infectious Diseases No Responses »

Oct 202010

Two major genera of hookworms, which are nematodes or roundworms, infect humans. Necator americanus, the only representative of its genus, is a major anthropophilic hookworm and is the most common cause of human hookworm infection. Hookworms of the genus Ancylostoma includes the major anthropophilic hookworm Ancylostoma duodenale that also causes classic hookworm infection and the less common zoonotic species.

Life Cycle:

The infective larval stages of the anthropophilic hookworms live in a developmentally arrested state in warm, moist soil. Larvae infect humans either by penetrating through the skin (N. americanus and A. duodenale) or when they are ingested (A. duodenale). Larvae entering the human host by skin penetration undergo extraintestinal migration through the venous circulation and lungs before they are swallowed, whereas orally ingested larvae may undergo extraintestinal migration or remain in the gastrointestinal tract. Larvae returning to the small intestine undergo 2 molts to become adult sexually mature male and female worms ranging in length from 5 to 13 mm.

Epidemiology:

Hookworm infection is 1 of the most prevalent infectious diseases of humans, affecting an estimated 576 million individuals worldwide. Because of the requirement for adequate soil moisture, shade, and warmth, hookworm infection is usually confined to rural areas, especially where human feces are used for fertilizer or where sanitation is inadequate. Hookworm is an infection associated with economic underdevelopment and poverty throughout the tropics and subtropics. Sub-Saharan Africa, East Asia, and tropical regions of the Americas have the highest prevalence of hookworm infection.

Pathogenesis:

The major morbidity of human hookworm infection is a direct result of intestinal blood loss. Adult Continue reading »

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Introduction to Thiamine (Vitamin B1)

Nutrition No Responses »

Oct 182010

Thiamine (vitamin B₁) provides the functional group for the coenzyme thiamine pyrophosphate, which is involved in decarboxylation of pyruvate and ?-ketoglutarate and, thus, is important in the release of energy from carbohydrates. It also participates in the hexose monophosphate shunt that generates nicotinamide adenine dinucleotide phosphate and pentose.

Thiamine also is required for the synthesis of acetylcholine, and deficiency results in impaired nerve conduction.

Good sources of thiamine include meat (especially lean pork), legumes, and cereals. Unless enriched, refined cereals and flours have a much lower content of thiamine than whole grains. The vitamin is easily destroyed by heat, particularly in alkaline media, and significant amounts are lost in discarded cooking water. The breast milk of a well-nourished mother provides adequate thiamine; breast-fed infants of thiamine-deficient mothers, however, are at risk for deficiency. Most infants and older children obtain an adequate intake of thiamine from food and do not require supplements.

Thiamine is absorbed efficiently in the gastrointestinal tract, but may be decreased in persons with gastrointestinal or liver disease.

Deficiency (beriberi) has been reported in adolescents after gastric bypass surgery. Intakes in excess of tissue needs are excreted in the urine. Fever and/or stress may increase the requirement for thiamine and unmask marginal thiamine sufficiency, but these factors are unlikely to cause deficiency.

Thiamine dependence has been described in a child with megaloblastic anemia and in an infant Continue reading »

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