An 8-month-old child was brought to the emergency department with cough, fever, and breathlessness. Physical examination confirmed the diagnosis of pneumonia. The medical record of the child showed that this child had four attacks of pneumonia in the last four months. Given these and the family history, cystic fibrosis was suspected and sweat test was requested and showed a slightly raised chloride. Conditions other than cystic fibrosis might increase sweat chloride concentration and result in false positive results. One of these is:
Correct Answer D: After the primary sweat secretion is produced in the body of the sweat gland, the ducts reabsorb sodium and chloride. With high sweat flow rates, the ducts would have little time to reabsorb large amounts of sodium and chloride resulting high levels of these ions in collected sweat (Choice D).
→ Dehydration, by decreasing the effective renal blood flow, stimulates aldosterone secretion. As in the renal tubules, aldosterone would stimulate reabsorption of sodium and chloride by the ducts of sweat glands. A false negative, rather than false positive result is expected with dehydration.
→ Hypovolemia has an effect similar to dehydration.
→ Steroids, even if they are of the glucocorticoid type like cortisol would some mineralocorticoid activity. A false negative rather than false positive is expected.
→ The generalized edema of congestive heart is partly due to secondary aldosteronism. A false negative is more likely than false positive.
Key point:
Although measurement of sweat chloride level is probably the most useful test in diagnosis of cystic fibrosis, false positive test result is possible. The collection process of sweat should thus, be standardized and the hemodynamic stability of the patient optimized before sweat collection.
A 9-year-old boy is brought to the pediatric clinic by his mother, who noticed that the left side of his mouth has started to droop over the past several days. In addition, he is unable to close his left eye completely and says that it is burning. Review of systems reveals a cold approximately two weeks ago and recent decreased taste sensation. There is left eye ptosis and mild erythema of the left conjunctiva. His smile is asymmetrical on the left.
Which of the following infections is most closely associated with this patient's condition?
Correct Answer A: This patient has Bell's palsy, a postinfectious allergic or immune demyelinating facial neuritis. Epstein Barr Virus (EBV) (choice A) is the preceding infection in approximately 20% of cases. 85% of patients have their symptoms resolve on their own over a period of several weeks. 10% retain mild facial weakness and 5% have permanent severe facial weakness. Therapeutic intervention should include daily and nocturnal eye lubricants to protect the cornea from drying.
→ Group A Streptococcus (choice B), HIV (choice C), and influenza (choice D) are not associated with Bell's palsy. However, herpes simplex virus, Lyme disease caused by Borrelia burgdorferi and mumps have been associated with Bell's palsy.
→ Measles (choice E) is associated with subacute sclerosing panencephalitis, a chronic encephalitis of the central nervous system manifested by progressively bizarre behavior and decline in cognitive function.
A child suffering from constipation, decreased activity and poor feeding is shown here. The mother says that overall he is a "good baby" since he rarely cries and sleeps most of the time. You notice a large protruding tongue.
What is the most likely diagnosis?
Correct Answer A: Cretinism is a condition of severely stunted physical and mental growth due to untreated congenital deficiency of thyroid hormones (hypothyroidism).
Children with hypothyroidism may develop excessive sleeping, reduced interest in nursing, poor muscle tone, low or hoarse cry, infrequent bowel movements, exaggerated jaundice, and low body temperature. Physical features may include a larger anterior fontanel, persistence of a posterior fontanel, an umbilical hernia, and a large tongue (macroglossia). Often, they are described as "good babies" because they rarely cry and sleep most of the time.
In the developed world, nearly all cases of congenital hypothyroidism are detected by the newborn screening program. These are based on measurement of TSH or thyroxine (T4) on the second or third day of life. If the TSH is high, or the T4 low, the infant's doctor and parents are called and a referral to a pediatric endocrinologist is recommended to confirm the diagnosis and initiate treatment.
The goal of newborn screening programs is to detect and start treatment within the first 1-2 weeks of life. Treatment consists of a daily dose of thyroxine, available as a small tablet.
Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18) and Patau syndrome (Trisomy 13) would not present like this.
A 14-week-old infant is brought to the office for a visit. His mother states that he has been a very slow eater and that he is constipated, not having had a bowel movement in 3 days. On physical examination, the infant has poor muscle tone, an enlarged tongue, an umbilical hernia, an enlarged anterior fontanelle, and hypothermia. He also looks slightly jaundiced, with slightly dry skin and brittle hair.
Which of the following is the most likely diagnosis?
Correct Answer B: The signs and symptoms of congenital hypothyroidism may not be obvious for several weeks. Symptoms include physical sluggishness, constipation, large tongue, umbilical hernia, hypothermia, bradycardia, enlarged fontanels, and persistent jaundice. Skin may be dry and scaly, and the hair may be dry, coarse, and brittle.
A 4-year-old child has ingested a large number of iron tablets.
What is likely to be the first symptom?
Correct Answer A: Acute iron intoxication seen exclusively in young children, where even small numbers of tablets can be fatal. Symptoms will be initially vomiting, abdominal pain, bloody diarrhea and then later shock, lethargy, dyspnea and severe metabolic acidosis.
Treatment involves whole bowel irrigation to remove un-absorbed tablets. Deferoxamine is given to remove absorbed tablets. Activated charcoal can’t bind to iron, so will have no benefit.
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