Vitamin A Deficiency Due to Selective Eating as a Cause of Blindness in a High-Income Setting.

Vitamin A is a fat-soluble micronutrient involved in the regulation of several physiologic functions, such as visual acuity, epithelial tissue integrity, immune response, and gene expression, thus playing a crucial role in childhood growth and development. Although vitamin A deficiency (VAD) in resource-limited settings is still an actual issue and represents the leading cause of preventable childhood blindness, its occurrence in high-income countries is rare, although possibly underdiagnosed because of its nonspecific early manifestations. A good awareness of VAD symptoms and risk factors could aid its early diagnosis, which is fundamental to undertake a prompt treatment and to prevent ocular complications. Nevertheless, the role of restrictive dietary habits, increasingly common in developed countries, is often overlooked in infants and children. We present a case of VAD with permanent ocular sequelae in a 5-year-old girl from a high-income country. In the case described, VAD ensued from a highly restricted diet, mainly limited to oat milk, which had been followed for more than 2 years. This child presented with ocular symptoms, opportunistic infection, anemia, poor growth, and a diffuse squamous metaplasia of the bladder; after commencing retinol supplementation, a gradual healing of clinical VAD manifestations occurred, with the exception of the ocular sequelae, which resulted in irreversible visual loss.

Comparison between liquid and tablet formulations of levothyroxine in the initial treatment of congenital hypothyroidism.

OBJECTIVE: To evaluate the effects of liquid (drops) and tablet formulations of levothyroxine in homogeneous groups of infants with congenital hypothyroidism (CH) as diagnosed through neonatal screening. STUDY DESIGN: Forty-two consecutive infants with CH were subdivided into 2 groups consisting of infants with the severe or the moderate/mild form. For each form, the infants with CH were randomly assigned to receive liquid (group 1) or tablet (group 2) formulation. In all patients, thyroid function tests were performed before the beginning of therapy and at 15 and 30 days and at 3 and 6 months after the beginning of therapy. RESULTS: In the severe form, after 15 days of treatment, serum thyrotropin (TSH) levels became normal in 8 of 9 patients in group 1 and in 5 of 9 patients in group 2; serum free triiodothyronine (fT3) levels were significantly higher in group 1 than in group 2; and serum fT4 levels were higher than the upper limit of the normal range in all patients in both groups. During the follow-up, there were significantly more patients with suppressed TSH concentrations in group 1 than in group 2. In the moderate/mild form, the patients of group 1 and group 2 showed median values of TSH, fT3, and fT4 that were not significantly different. No clinical or electrocardiographic signs of heart disease were found. There were no significant differences in the developmental quotient between group 1 and group 2 patients with severe and moderate/mild CH. CONCLUSIONS: Our data seem to indicate that there is not complete bioequivalence between drops and tablets, especially in infants with severe CH.

Current loss-of-function mutations in the thyrotropin receptor gene: when to investigate, clinical effects, and treatment.

Thyroid-stimulating hormone receptor (TSHR) loss-of-function (LOF) mutations lead to a wide spectrum of phenotypes, ranging from severe congenital hypothyroidism (CH) to mild euthyroid hyperthyrotropinemia. The degree of TSH resistance depends on the severity of the impairment of the receptor function caused by the mutation and on the number of mutated alleles In this review data about genotype-phenotype correlation and criteria for clinical work-up will be presented and discussed. Complete TSH resistance due to biallelic LOF TSHR mutations must be suspected in all patients with severe not syndromic CH and severe thyroid hypoplasia diagnosed at birth by neonatal screening. Partial forms of TSH resistance show a more heterogeneous hormonal and clinical pattern . In these cases TSH serum levels are above the upper limit of normal range for the age but with a very variable pattern, free thyroxine (T4) concentrations are within the normal range and thyroid size can be normal or hypoplastic at ultrasound scan. An early substitutive treatment with L-T4 must be mandatory in all patients with severe CH due to complete uncompensated TSH resistance diagnosed at birth by neonatal screening. The usefulness of substitutive treatment appears much more controversial inpatients with subclinical hypothyroidism due to partial TSH resistance in whom the increased TSH concentration should be able to compensate the mild functional impairment of the mutant receptor. Together with standard criteria we recommend also an accurate clinical work-up to select patients who are candidates for a LOF TSHR mutation.