Congenital hypothyroidism presenting with reversible renal impairment: an under-recognised problem?
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Hypothyroidism with impairment of renal function and raised creatinine phosphokinase (CPK) is described in adults and children with acquired hypothyroidism, but not in congenital hypothyroidism.
A male infant born at term weighing 3390 g was seen aged 2 months with prolonged jaundice. Examination showed somnolence, umbilical hernia, enlarged fontanelles and lower limb edema; length 55 cm (−1.5 SD), weight 5.4 kg (−0.13 SD). Biochemistry showed fT4 < 1 pmol/L, TSH = 1044.36 μUI/mL, creatinine 77 μmol/L(normal <35 μmol/L), estimated glomerular filtration rate (GFR) 26 ml/min/1.73 m2, CPK 3952.5 IU/L (normal<400 IU/L). Ultrasound showed no thyroid tissue in the neck. In view of the renal impairment, peritoneal dialysis was initially contemplated but postponed and the child received levothyroxine 10 μg/kg/day. Two months later thyroid function tests, CPK and renal function had all normalized with creatinine 19 μmol/L and GFR 116 ml/min/1.73m2.
Reversible renal impairment is attributable to severe congenital hypothyroidism causing decreased myocardial contractility and cardiac output and to a direct effect on the kidneys. Thyroid function should be checked in infants with renal impairment of unknown cause. Cautious fluid management is indicated in hypothyroid infants. Hypothyroidism may also be associated with elevated serum CPK levels but resolves with thyroxin therapy.
KeywordsThyroid Renal insufficiency Congenital hypothyroidism
This study couldn’t have been carried out without the parents being as interested as we were in understanding their child’s evolving situation. We thank them for their permission and willingness to report this case so as to be useful to other children.
The authors would also like to thank Dr. Malcolm Donaldson for his careful review, valuable assistance, helpful suggestions and enthusiastic support.
Compliance with ethical standards
Conflict of interest
All the authors declare that they have no conflict of interest.
All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments.
Informed consent was obtained from the child’s parents.