The infant is highly irritable with incessant high pitched c

Discussion in 'USMLE STEP 2 CS' started by DRjames., Aug 26, 2008.

  1. DRjames.

    DRjames. Guest

    A 3-week-old African American boy is brought to the Emergency Department because of a generalized seizure 2 hours ago. The infant is highly irritable with incessant high pitched crying. The infant's weight is 2.5 kg (250 gm below birth weight), blood pressure is 70 /40 mm Hg, pulse is 145/min and respirations are 50/min. Laboratory results show: Blood glucose 120 mg/dL
    Urea nitrogen 50 mg/dL
    Serum sodium 170 mEq/L
    Serum calcium 8.5 mg/dL
    Serum magnesium 1.5 mg/dL


    Which of the following is the most likely cause of this infants seizure?


    A. Hypocalcemia
    B. Hypoglycemia
    C. Hypomagnesemia
    D. Intracranial hemorrhage
    E. Meningitis
  2. Guest

    Guest Guest

    The answer is 4.
    The level of serum sodium in this patient is 170 mEq/L. Infants who have hypernatremic dehydration are irritable and lethargic, and have a high-pitched cry. This type of dehydration results from a greater loss of hypotonic fluid than sodium and accounts for about 15% of cases of dehydration. Because the patient has no history of diarrhea or vomiting, the hypernatremia may be due to inadequate supply of mother's milk that does not match the insensible water loss. Another cause can be the high concentration of sodium in mother's milk. Generally, after the child's birth, sodium in the colostrum decreases from its highest level to its lowest level by the fourth week. However, some mothers continue to excrete high sodium in their milk and can potentially cause recurrent hypernatremia and in some cases, intracranial hemorrhage in the infant.

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