The increased incidence of congenital hypothyroidism: fact or fancy?

OBJECTIVE: The incidence of congenital hypothyroidism (CH) detected by newborn screening in the US has increased significantly since the early 1990s. We defined the characteristics associated with the increased incidence. PATIENTS: A cohort of children with CH born during an earlier period of low incidence (1991-94) was compared with a cohort born during a later period when the incidence of CH had doubled (2001-04). MEASUREMENTS: Screening was performed with T4 as the primary marker and thyroid stimulating hormone (TSH) on selected specimens. Follow-up on hypothyroid children determined whether they had permanent or transient hypothyroidism. Cases were classified based on laboratory results: initial TSH ≥100 mU/l was 'severe,' initial TSH <100 mU/l but ≥20 mU/l was 'mild' and initial TSH <20 mU/l with subsequent abnormal TSH was 'delayed'. RESULTS: The overall incidence of CH almost doubled between the two time periods, from 1:3010 to 1:1660. Excess cases were found in the mild and delayed categories, with no increase in severe cases. The proportion of transient cases was <5% in severe cases, 40% in mild cases and 70% among delayed cases. There was no difference in the proportion of transient case between the two time periods. Modifications to the T4/TSH testing protocol between the two time periods resulted in substantially increased numbers of specimens in the younger cohort being selected for TSH testing in both initial and repeat specimens. CONCLUSION: The rising incidence of CH in Massachusetts is confined to mild and delayed cases. Our findings suggest that this rise is attributable to enhanced detection rather than an absolute increase in numbers.

Hypothyroidism in Infants With Congenital Heart Disease Exposed to Excess Iodine.

Thyroid hormone is critical for neonatal brain development, and even transient hypothyroidism can cause adverse neurocognitive outcomes. Infants exposed to excess iodine are at risk of developing hypothyroidism, especially those with congenital heart disease (CHD), because they are routinely exposed to excess iodine from intravenous iodinated contrast media and topical antiseptics. The aim of the present study was to identify the proportion of neonates with CHD exposed to iodine who developed hypothyroidism and to identify the associated risk factors. This was a retrospective study of neonates undergoing cardiac catheterization at Boston Children's Hospital during a 3-year period, some of whom also underwent cardiac surgery. Hypothyroidism was defined as an elevated thyroid-stimulating hormone level (>20 mIU/L at 24 to 96 hours of age and >15 mIU/L at >96 hours of age by heel-stick sampling and >9.1 mIU/L at 1 to 20 weeks of age by serum testing). Multivariate logistic regression was performed to predict the odds of developing hypothyroidism. Hypothyroidism was diagnosed incidentally in 46 of 183 infants (25%) with CHD after iodine exposure. Controlling for baseline cardiac risk, postnatal age, and gestational age, we found a fourfold increase in odds of developing hypothyroidism in neonates with serum creatinine >0.9 mg/dL and a fourfold increase in those who underwent more than three procedures. Hypothyroidism in neonates with CHD exposed to excess iodine is associated with multiple procedures and impaired renal function. Routine serial monitoring of thyroid function in these neonates is warranted. Future studies should examine the association between hypothyroidism and neurocognitive function in this population.

Hospitalization trends among children and youths with perinatal human immunodeficiency virus infection, 1990-2002.

BACKGROUND: Major improvements in disease progression among HIV-infected children have followed the adoption of combination antiretroviral therapy. METHODS: We examined trends in hospitalization rates between 1990-2002 among 3,927 children/youths with perinatal HIV infection, ranging in age from newborn to 21 years. We used Poisson regression to test for trends in hospitalization rates by age and year; binomial regression to test for trends in intensive care unit (ICU) admissions and hospitalization at least once and more than once, by age and year; and multivariate logistic regression to examine factors associated with hospitalization, ICU admission, and hospitalization longer than 10 days. RESULTS: Statistically significant downward trends in hospitalization rates and multiple hospitalizations were observed in all age groups from 1990-2002. The proportion of HIV-infected children/youths who were hospitalized at least once declined from 30.4% in 1990 to 12.9% in 2002, with a steady decline occurring after 1996, when the U.S. Public Health Service issued guidelines recommending triple-drug antiretroviral therapy (triple therapy) for HIV-infected children. ICU admissions declined significantly in all age groups except among children younger than 2 years. Logistic regression results indicated that black and Hispanic children/youths were significantly more likely to be hospitalized than white children/youths and that children/youths receiving triple therapy were significantly more likely to be hospitalized than therapy-naive children; the latter association was not observed among children monitored from 1997-2002. CONCLUSIONS: Substantial reductions in rates of hospitalization, multiple hospitalizations, and ICU admission have occurred among HIV-infected children/youths from 1990-2002, particularly after 1996, with increased use of triple therapy.

Changing perspectives in screening for congenital hypothyroidism and congenital adrenal hyperplasia.

PURPOSE OF REVIEW: The purpose of this review is to summarize recent information that has had a significant impact on the laboratory diagnosis and clinical management of newborns with congenital hypothyroidism and congenital adrenal hyperplasia (CAH). RECENT FINDINGS: An approximate doubling of the incidence rate of congenital hypothyroidism in many parts of the world has been attributed to increased detection of infants with mild disease, delayed thyroid stimulating hormone elevations and demographic changes. A substantial number of children with modest thyroid stimulating hormone elevations on screening have permanent disease. Circulating levels of thyroxine may vary among hypothyroid children who are given identical dosages of medication. Treated infants should be monitored every 1-2 months during the first year of life. Although, generic and brand name thyroxine preparations may not be bioequivalent, children can be well controlled on generic formulations.Enzyme linked immunoassay assay for 17-hydroxyprogesterone is associated with a high rate of false positive specimens. In attempts to minimize this problem, some programs have resorted to two-tier screening of the initial specimen with steroid profiling as the second tier. Several programs are routinely testing second specimens in an effort to reduce the incidence of missed CAH cases. SUMMARY: This review explains the uptick in incidence rate of congenital hypothyroidism and underscores issues in management that can affect developmental outcome. One specimen two-tier testing for CAH resulted in an increased false negative rate without significantly reducing the false positive rate. The benefit of collecting second specimens for CAH screening is problematic. Optimal treatment of CAH continues to pose a challenge.

Spectrum of medium-chain acyl-CoA dehydrogenase deficiency detected by newborn screening.

OBJECTIVE: Our goal was to describe the clinical spectrum of medium-chain acyl-CoA dehydrogenase deficiency detected by routine newborn screening and assess factors associated with elevations of octanoylcarnitine in newborns and characteristics associated with adverse clinical consequences of medium-chain acyl-CoA dehydrogenase deficiency. METHODS: The first 47 medium-chain acyl-CoA dehydrogenase deficiency cases detected by the New England Newborn Screening Program were classified according to initial and follow-up octanoylcarnitine values, octanoylcarnitine-decanoylcarnitine ratios, medium-chain acyl-CoA dehydrogenase genotype, follow-up biochemical parameters, and feeding by breast milk or formula. RESULTS: All 20 patients who were homozygous for 985A-->G had high initial octanoylcarnitine values (7.0-36.8 microM) and octanoylcarnitine-decanoylcarnitine ratios (7.0-14.5), whereas the 27 patients with 0 to 1 copy of 985A-->G exhibited a wide range of octanoylcarnitine values (0.5-28.6 microM) and octanoylcarnitine-decanoylcarnitine ratios (0.8-12.7). Initial newborn octanoylcarnitine values decreased by days 5 to 8, but the octanoylcarnitine-decanoylcarnitine ratio generally remained stable. Among 985A-->G homozygotes, breastfed newborns had higher initial octanoylcarnitine values than newborns who received formula. Adverse events occurred in 5 children, 4 985A-->G homozygotes and 1 compound heterozygote with a very high initial octanoylcarnitine: 2 survived severe neonatal hypoglycemia, 1 survived a severe hypoglycemic episode at 15 months of age, and 2 died as a result of medium-chain acyl-CoA dehydrogenase deficiency at ages 11 and 33 months. CONCLUSION: Newborn screening for medium-chain acyl-CoA dehydrogenase deficiency has detected cases with a wide range of genotypes and biochemical abnormalities. Although most children do well, adverse outcomes have not been entirely avoided. Assessment of potential risk and determination of appropriate treatment remain a challenge.

Trends in antiretroviral therapy use and survival rates for a large cohort of HIV-infected children and adolescents in the United States, 1989-2001.

BACKGROUND: In the United States, HIV-infected children and adolescents are aging and using antiretroviral (ARV) therapy for extended periods of time. OBJECTIVE: To assess trends in ARV use and long-term survival in an observational cohort of HIV-infected children and adolescents in the United States. METHODS: The Pediatric Spectrum of HIV Disease Study (PSD) is a prospective chart review of more than 2000 HIV-infected children and adolescents. Patients were included in the analysis from enrollment until last follow-up. RESULTS: Triple-ARV therapy use (for 6 months or more) increased from 27% to 66% during 1997 to 2001 (P < 0.0001, chi for trend). The proportion of patients receiving 3 or more sequential triple-therapy regimens also increased from 4% to 17% during 1997 to 2001 (P < 0.0001, chi for trend), however, and the durability of triple-therapy regimens decreased from 13 to 7 months from the first to third regimen. Survival rates for the 1997 to 2001 birth cohorts were significantly better than for the 1989 to 1993 and 1994 to 1996 cohorts (P < 0.0001). CONCLUSIONS: Survival rates in the PSD cohort have increased in association with triple-ARV therapy use. With continued changes in ARV regimens, effective modifications in ARV therapy and the sustainability of gains in survival need to be determined.

Missed opportunities for perinatal HIV prevention among HIV-exposed infants born 1996-2000, pediatric spectrum of HIV disease cohort.

OBJECTIVE: Despite dramatic reductions in perinatal human immunodeficiency virus (HIV) transmission in the United States, obstacles to perinatal HIV prevention that include lack of prenatal care; failure to test pregnant women for HIV before delivery; and lack of prenatal, intrapartum, or neonatal antiretroviral (ARV) use remain. The objective of this study was to describe trends in perinatal HIV prevention methods, perinatal transmission rates, and the contribution of missed opportunities for perinatal HIV prevention to perinatal HIV infection. METHODS: We analyzed data obtained from infant medical records on 4755 HIV-exposed singleton deliveries in 1996-2000, from 6 US sites that participate in the Centers for Disease Control and Prevention's Pediatric Spectrum of HIV Disease Project. HIV-exposed deliveries refer to deliveries in which the mother was known to have HIV infection during the pregnancy. RESULTS: Of the 4287 women with data on prenatal care, 92% had prenatal care. From 1996 to 2000, among the 3925 women with prenatal care, 92% had an HIV test before delivery; the use of prenatal zidovudine (ZDV) alone decreased from 71% to 9%, and the use of prenatal ZDV with other ARVs increased from 6% to 70%. Complete data on maternal and neonatal ARVs were available for 3284 deliveries. Perinatal HIV transmission was 3% in 1651 deliveries with prenatal ZDV in combination with other ARVs, intrapartum ZDV, and neonatal ZDV; 6% in 1111 deliveries with prenatal, intrapartum, and neonatal ZDV alone; 8% in 152 deliveries with intrapartum and neonatal ZDV alone; 14% of 73 deliveries with neonatal ZDV only started within 24 hours of birth; and 20% in 297 deliveries with no prenatal, intrapartum, and neonatal ARVs. Complete data on prenatal events were available in 328 HIV-infected and 3258 HIV-uninfected infants. A total of 56% of mothers of HIV-infected infants had missed opportunities for perinatal HIV prevention versus 16% of mothers of HIV-uninfected infants. Forty-four percent of the infected infants were born to mothers who had prenatal care, a prenatal HIV diagnosis, and documented prenatal ARV therapy. Seventeen percent of women with reported illicit drug use had no prenatal care versus 3% of women with no reported drug use. In a multivariate analysis, maternal illicit drug use was significantly associated with lack of prenatal care. In a multivariate analysis, year of infant birth and the combination of lack of maternal HIV testing before delivery and lack of prenatal antiretroviral therapies were significantly associated with perinatal HIV transmission. CONCLUSIONS: Missed opportunities for perinatal HIV prevention contributed to more than half of the cases of HIV-infected infants. Prenatal care and HIV testing before delivery are major opportunities for perinatal HIV prevention. Illicit drug use was highly associated with lack of prenatal care, and lack of HIV testing before delivery was highly associated with perinatal HIV transmission.

Increasing trend of Cesarean deliveries in HIV-infected women in the United States from 1994 to 2000.

BACKGROUND: Meta-analysis and randomized clinical trial results reported in June 1998 indicated a significant reduction in perinatal HIV transmission rates among mothers undergoing a cesarean section (C-section). OBJECTIVE: The objective of this study was to examine recent trends in and factors associated with C-section deliveries among HIV-infected women in the United States. DESIGN: A multisite pediatric medical record review of a cohort of HIV-exposed and HIV-infected infants in the Pediatric Spectrum of HIV Disease (PSD) Cohort study (n = 6467) and the national Pediatric HIV/AIDS Reporting System (HARS) (n = 8,306) was conducted. SETTING/PATIENTS: All infants born between 1994 and 2000 to HIV-positive mothers referred to the PSD study or to a Pediatric HARS hospital or clinic site were enrolled. RESULTS: The proportion of deliveries by C-section was steady at about 20% from 1994 through June 1998. From July 1998 through December 2000, this proportion increased to 44% in the PSD study and to nearly 50% in the Pediatric HARS. On analysis by multiple logistic regression, delivery of infants by C-section was associated with the release of study results (OR = 2.83), delivery in four PSD sites in reference to Texas (OR: 2.02-1.43), having private medical care reimbursement (OR = 1.62), and having maternal prenatal care (OR = 1.43). CONCLUSIONS: The PSD and Pediatric HARS data demonstrate a sharp increase in C-section rates mainly among HIV-infected women in the United States after the release of the meta-analysis and randomized clinical trial results in 1998. This finding highlights the rapid impact of study results on obstetric practice. It underscores the critical role of prenatal care in offering perinatal interventions such as scheduled C-section when indicated to reduce the likelihood of HIV transmission.