Misdiagnosis of cystic fibrosis. Need for continuing follow-up and reevaluation.

A retrospective review was conducted of the charts of 271 patients with a diagnosis of cystic fibrosis (CF) who were evaluated over a 15-year period at the Johns Hopkins Hospital. Among these patients, eight were encountered in which the diagnosis of CF was made on the basis of a compatible clinical picture and at least two positive quantitative pilocarpine iontophoresis sweat tests but who were subsequently documented to have normal sweat electrolyte concentrations. Six of the eight patients had recurrent episodes of cough and wheezing without evidence of suppurative pulmonary disease. Our experience suggests that variability in sweat electrolyte concentrations may occur more commonly than is generally appreciated. In those patients who do not follow a typical course, it is crucial to repeat sweat tests, even if the initial diagnosis was based on two or more positive quantitative pilocarpine iontophoresis sweat tests performed in a CF referral center.

Cystic fibrosis in adults: delayed diagnosis in three siblings.

Cystic fibrosis (CF), which is transmitted as an autosomal recessive trait, is the most common lethal genetic disease in the United States. Median survival age for patients followed up at CF centers in the US is now 21 years. While the disease is diagnosed in most patients before the age of 5 years, in 10% of cases the diagnosis is not confirmed until after age 12. We report an unusual family in which the diagnosis of CF was first established in three siblings at the ages of 36, 40, and 44 years. We describe the clinical features of the patients, as well as issues relating to the diagnosis of CF in adults. This unusual pedigree supports the concept of genetic heterogeneity in CF.

Diagnosis of cystic fibrosis during adolescence.

The manifestations of cystic fibrosis (CF) may be minimal, absent, or overlooked during childhood, thus 8-10% of cases are diagnosed during adolescence. Between 1970 and 1982, 14/157 (8.9%) patients were diagnosed as having CF as teenagers, based on clinical findings and elevated sweat electrolyte levels. Of these 14 patients (means = 15 years, range = 12-20 years), 50% had pulmonary and gastrointestinal symptoms dating from childhood; 50% became symptomatic during adolescence (primarily with pulmonary manifestations). None had a family history of CF. Four had false-negative sweat tests resulting in a mean diagnostic delay of 7.3 years. Because of the potential long-term complications of CF on physical maturation, completion of the psychosocial tasks of adolescence, adaptation to a chronic illness, and issues of sexuality and fertility, consideration of this diagnosis is crucial.

Unexpected diagnosis of cystic fibrosis at autopsy.

Over an 11-year period, we encountered four cases in which an unexpected diagnosis of cystic fibrosis (CF) was first established on the basis of typical autopsy findings. Our experience suggests that the occurrence of such cases is more common than generally appreciated and emphasizes the often crucial role of the autopsy in medical practice.

Incidence of distal intestinal obstruction syndrome in cystic fibrosis.

A variety of intestinal complications, including constipation, abdominal pain, palpable cecal masses, intestinal obstruction, intussusception, and volvulus, have been observed beyond the neonatal period in patients with cystic fibrosis (CF). In a retrospective chart review of 63 patients with CF, we found evidence of one or more of these complications in 26 patients (41.3%). The incidence of intestinal complications was not related to overall disease severity, pulmonary exacerbations, history of meconium ileus at birth, or dose or type of pancreatic enzyme replacement. There was no change in the incidence of intestinal complications after patients switched to a pH-sensitive enteric-coated microsphere enzyme preparation.

Incidence of meconium abnormalities in newborn infants with cystic fibrosis.

Review of the newborn nursery notes of 87 infants who had cystic fibrosis without meconium ileus (MI) indicated that 12 of them had clinical features consistent with the meconium plug syndrome (MPS). This high incidence of meconium abnormalities suggests that MI and the MPS probably represent different gradations of the same underlying pathologic abnormality. The findings further suggest that a quantitative pilocarpine iontophoresis sweat test be performed in every newborn infant with any type of meconium abnormality, including the spontaneous passage of meconium plugs.

Cystic fibrosis. Problems encountered with sweat testing.

The sweat test is the only practical and reliable laboratory test for confirmation of the diagnosis of cystic fibrosis. Among 234 patients referred to The Johns Hopkins Hospital for sweat testing, 62 had had a previous test; 29 tests had been reported as negative, and 33 tests had been reported as positive. Results of quantitative pilocarpine-iontophoresis sweat tests at this center led to a change in diagnosis in 27 (43.5%) of these 62 patients. Most of the errors were false-positive.