Neonatal screening for congenital primary hypothyroidism (CH) may not distinguish between transient (TCH) and permanent dysfunction (PCH), causing potential overtreatment and concerns in affected families. To specify the indication for interruption of therapy, we analysed the German registry “HypoDok” for infants with CH, which oversees 1625 patients from 49 participating centres in Germany and Austria from 1997 until today. A total of 357 patients with a thyroid gland in loco typico were identified and retrospectively grouped according to cessation (TCH, n = 24) or continuation (PCH, n = 333) of l-thyroxine (l-T4) treatment at 2 years of age. The receiver operating characteristic (ROC) analysis was performed to identify cutoffs predicting TCH by screening TSH concentrations and l-T4 dosages. Gestational ages, birth weights and prevalence of associated malformations were comparable in both groups. The cutoff screening TSH concentration was 73 mU/L. The cutoff daily l-T4 dosage at 1 year was 3.1 μg/kg (90% sensitivity, 63% specificity; 36 μg/day) and at 2 years of age 2.95 μg/kg (91% sensitivity, 59% specificity; 40 μg/day). At 2 years of age, specificity (71%) increased when both of these parameters were considered together.Conclusion: The decision to continue or cease l-T4 treatment at 2 years of age in CH patients diagnosed in neonatal screening may be based on their screening TSH concentrations and individual l-T4 dosages at 1 and 2 years of age. Thus, TCH and PCH may be distinguished; overtreatment avoided; and affected families reassured. What is Known:• The course of congenital primary hypothyroidism may be transient, causing potential overtreatment.• The dose ofl-thyroxine at 1 or 2 years of age may predict a transient course of primary congenital hypothyroidism. What is New:• TSH screening concentration andl-thyroxine dosages at 1 and 2 years of age represent reliable predictors for transient congenital primary hypothyroidism with higher sensitivity and specificity when considered together in order to select eligible patients who qualify for treatment withdrawal.

Background Iatrogenic Cushing’s syndrome induced by oral and parenteral glucocorticoid administration is a well-known complication. Immediate withdrawal from exogenous steroids can lead to life-threatening adrenal insufficiency. However, Cushing’s syndrome caused by topical treatment with glucocorticoids, such as dexamethasone eye drops or dermal application, is rarely recognized. Young infants in particular are at high risk of suffering from iatrogenic Cushing’s syndrome when treated with highly potent topical glucocorticoids. Case presentation We present a 6-month-old Syrian boy with cushingoid face after dermal clobetasol cream treatment and a 2-year-old Iranian girl with severe growth retardation after application of dexamethasone eye drops. Both families have a migration background and language barriers. In both cases no endogenous cortisol secretion was initially detected in serum and in 24-hour collected urine. After dose reduction of glucocorticoids, severity of symptoms was reversible and serum cortisol was detectable. Discussion and conclusion Young infants are at high risk of developing Cushing’s syndrome from topically applied highly potent glucocorticoids. Precise recommendations of treatment dosage, duration, and frequency must be given to the parents, and if necessary, with the help of an interpreter. Monitoring of height and weight as well as regular pediatric follow-ups should be scheduled. Physicians should be aware of potential adrenal insufficiency following withdrawal from long-term topical glucocorticoid treatment, and hydrocortisone treatment should be considered.

Neonatal screening for congenital primary hypothyroidism (CH) may not distinguish between transient (TCH) and permanent dysfunction (PCH), causing potential overtreatment and concerns in affected families. To specify the indication for interruption of therapy we analysed the German registry "HypoDok" for infants with CH, which oversees 1,625 patients from 49 participating centres in Germany and Austria from 1997 until today. 357 Patients with a thyroid gland in loco typico were identified and retrospectively grouped according to cessation (TCH n=24) or continuation (PCH n=333) of L-Thyroxine (L-T4) treatment at 2 years of age. The receiver operating characteristic (ROC) analysis was performed to identify cut-offs predicting TCH by screening TSH concentrations and L-T4 dosages. Gestational ages, birth weights and prevalence of associated malformations were comparable in both groups. The cut-off screening TSH concentration was 73 mU/L. The cut-off daily L-T4 dosage at 1 year was 3.1 µg/kg (90% sensitivity, 63% specificity; 36 µg/d) and at 2 years of age 2.95 µg/kg (91% sensitivity, 59% specificity; 40 µg/d). At 2 years of age, specificity (71%) increased when these both parameters were considered together. Conclusion: The decision to continue or cease L-T4 treatment at 2 years of age in CH patients diagnosed in neonatal screening may be based on their screening TSH concentrations and individual L-T4 dosages at 1 and 2 years of age. Thus, TCH and PCH may be distinguished; overtreatment avoided, and affected families reassured.