Transient hypothyroidism

Replacement therapy is for life, witii the exception of transient hypothyroidism seen in those with tiiy-roiditis. 

Hypothyroidism As replacement or supplemental therapy in hypothyroidism of any etiology, except transient hypothyroidism during the recovery phase of subacute thyroiditis. 

Cytokines Interferon- and interleukin-2 - Therapy with interferon- has been associated with the development of antithyroid microsomal antibodies in 20% of patients and some have transient hypothyroidism, hyperthyroidism, or both. Patients who have antithyroid antibodies before treatment are at higher risk of thyroid dysfunction during treatment. Interleukin-2 has been associated with transient painless thyroiditis in 20% of patients. 

Extensive iodine absorption from povidone-iodine can cause transient hypothyroidism or in patients with latent hypothyroidism the risk of destabilization and thyrotoxic crisis (SEDA-20, 226 SEDA-22, 263). Especially at risk are patients with an autonomous adenoma, localized diffuse autonomy of the thyroid gland, nodular goiter, latent hyperthyroidism of autoimmune origin, or endemic iodine deficiency (51). 

Weber G, Vigone MC, Rapa A, Bona G, Chiumello G. Neonatal transient hypothyroidism aetiological study. Italian Collaborative Study on Transient Hypothyroidism. Arch Dis Child Fetal Neonatal Ed 1998 79(l) F70-2. 

MacFarlane IA, Shalet SM, Beardwell CG, Khara JS. Transient hypothyroidism after iodine-131 treatment for thyrotoxicosis. BMJ 1979 2(6187) 421. 

Iodine concentrations in breast milk and in random urine in neonates and the serum concentrations of neonatal TSH and free thyroxine on day 5 after delivery were measured after the use of povidone-iodine for disinfection after delivery (36). Iodine concentrations in the breast milk and neonatal TSH were significantly raised. Perinatal iodine exposure causes transient hypothyroidism in a significant number of neonates, in whom careful monitoring and follow-up of thyroid gland function are needed. It is better to avoid the use of iodine-containing antiseptics in pregnancy and neonates, especially if follow-up cannot be guaranteed. 

Serum TSH and thyroxine concentrations have been measured 57 days after birth in 365 healthy newborns whose umbilical stump had been treated with 10% povidone-iodine (41). The prevalence of high TSH concentrations was significantly higher in this group than in the general population (3.1% versus 0.4%), as was the rate of transient hypothyroidism (2.7% versus 0.25%). All the children were normal when retested 1 week later. Transient hypothyroidism due to skin contamination with povidone-iodine occurred in a neonate with an omphalocele (42). 

Scalp atresia has been described in an infant whose mother had taken carbimazole in a high dose (60 mg/ day) during the first 12 weeks of pregnancy and propylthiouracil thereafter (101). The infant had other dysmorphic features (a flat face, low-set ears, upper lip retraction, and a low-set fifth finger) in addition to transient hypothyroidism. 

Maayan-Metzger A, Sack J, Mazkereth R, Vardi A, Kuint J. Somatostatin treatment of congenital chylothorax may induce transient hypothyroidism in newborns. Acta Paediatr 2005 94 785-9. 

Giroux JD, Sizun J, Rubio S, Metz C, Montaud N, Guillois B, Alix D. Hypothyroldie transitoire apres opacification iodees des catheters epicutaneocaves au reanimation neonatale. [Transient hypothyroidism after iodine opacification of epicutaneo-caval catheters in neonatal intensive care.] Arch Fr Pediatr 1993 50 (3) 273. 

The main adverse effect of iodine-containing contrast agents after amniofetography is transient hypothyroidism, which has often been reported (236-246). 

Neonates are particularly sensitive to the effects of iodine, and transient hypothyroidism has often been reported, particularly in pre-term infants (237,252,253). The low glomerular filtration rate in infants can also result in delayed excretion of contrast agents. 

Bona G, Zaffaroni M, Perona A. Neonatal transient hypothyroidism after excess iodide exposition by amnio-fetography. Panminerva Med 1988 30(3) 192-3. 

Miething R. Transitorische Hypothyreose bei Fmh- nnd Neugeborenen nach Amniofetografie wahrend der Schwangerschaft. [Transient hypothyroidism after amniofetography in preterm and newborn infants.] Klin Padiatr 1981 193(5) 372-4. 

Rohner G, Rautenburg HW, Hopfner B. Transiente Hypothyreose bei Sauglingen nach Rontgenkontrastmittehi. [Transient hypothyroidism in infants following administration of roentgen contrast media.] Rontgenpraxis 1983 36(9) 301. ... 

Perinatal iodine exposure causes transient hypothyroidism in a significant number of neonates, in whom careful monitoring and follow-up of thyroid gland function are needed. It is better to avoid the use of iodine-containing antiseptics in pregnancy and neonates, especially if follow-up cannot be guaranteed. 

If a positive screening test is obtained, the mother s thyroid function is usually also assessed. Maternal autoantibodies can cross the placenta and block receptor sites on the fetal thyroid. In this rare situation, after an initial transient hypothyroidism just after birth, the baby s own thyroid function will usually develop normally. 

The studies, to date, of iodide toxicity in preterm infants exposed to iodinated contrast media are limited in number, with small cohorts and restricted information on confounders this is reflected in the wide range, 8-75%, of incidence of transient hypothyroidism. In the first study, a cohort of 13 preterm infants had features of transient hypothyroidism (Ares et ai, 1995). In the second study, a cohort of 12 infants had elevated TSH levels, but normal FT4 levels (Parravicini et ai, 1996) it is difficult to judge whether this was hyperthyrotropinemia alone or transient hypothyroidism, as T4 levels were not measured and FT4 levels can be exceptionally difficult to interpret in these infants (Williams et ai, 2004). In the third study six out of eight preterm infants had elevated TSH levels, with six suboptimalT4 levels (L Allemand et ai, 1987), indicating the majority had transient hypothyroidism. 

These studies suggest that transient hypothyroidism is common in preterm infants exposed to iodinated contrast media, and more frequent than complications arising from wrongly-positioned central venous catheters. We are unaware of any ongoing work in this area (e.g., there are none registered with National Research Register UK or the National Institute of Health USA). Because of the potential for permanent neurodevelopmental compromise in infants exposed to iodide toxicity, we believe that it is important to establish the true incidence of transient hypothyroidism associated with exposure to iodinated contrast media. 

Thyroxine is critical for the developing human brain and it is likely to be compromised whether serum T4 levels are reduced through transient hypothyroxinemia, with a contribution from iodine deficiency, or from transient hypothyroidism caused by iodine excess. 

The fetus and neonate are both at risk of developing iodine-induced hypothyroidism (Table 96.3). Many cases of such hypothyroidism in fetuses and neonates have been reported, especially in iodine-deficient regions of Europe, but also in iodine-sufficient areas. Iodide goiter in neonates is usually a transient problem. However, tracheal obstruction due to such goiter can be fatal (Markou et al, 2001 Wolff, 1969). Transient hypothyroidism without elevation of thyroid-stimulating hormone (TSH) in extremely... 

Women who have recendy been pregnant comprise an important subpopulation that is frequendy studied to elucidate the prevalence of hypothyroidism. While there are no large population-based reports to date, there are considerable data on the frequency of hypothyroidism in relatively small groups of patients. Postpartum lymphocytic thyroiditis results in transient hypothyroidism, with up to one quarter of patients eventually becoming permanently... 

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