Short Stature in Chronic Kidney Disease Treated with Growth Hormone and an Aromatase Inhibitor

Anastrozole Improves Final Adult Height in Severe Hypothyroidism With Rapid Pubertal Progression

Severe prolonged hypothyroidism due to Hashimoto thyroiditis may lead to rapid pubertal progression and compromised adult height after initiation of levothyroxine (LT4) therapy. There are no reports of aromatase inhibitor use to augment height in these patients. We describe a patient with severe hypothyroidism and growth failure who experienced rapid pubertal and bone age maturation on initiation of LT4 therapy. Anastrozole was added after 2 years to delay epiphyseal fusion. A boy aged 12 years and 1 month presented to the endocrine clinic with short stature and a markedly delayed bone age of 6 years. Brain magnetic resonance imaging showed a 1.5 × 1.0 × 1.2-cm enlarged lobular anterior pituitary. On examination, his height was -3.5 SD score (SDS) and weight was -2.87 SDS. Laboratory studies showed elevated thyrotropin (TSH) 850.6 μIU/mL, low free thyroxine 0.25 ng/dL, and elevated antithyroid antibodies. LT4 was initiated with normalization of TSH after 6 months. After 2 years of treatment he demonstrated catch-up growth with rapid bone age maturation, and his predicted adult height was compromised at 164.6 cm vs a midparental target height of 175.4 cm. Anastrozole 1 mg once daily was initiated. After 1.5 years of anastrozole treatment, the rate of his bone age advancement had slowed and his linear growth remained robust. The patient's near-final height (167 cm) was 2.4 cm taller than his height prediction prior to starting anastrozole. Anastrozole slowed the rate of bone age advancement in a patient with severe hypothyroidism and rapidly progressive puberty during treatment with LT4, leading to improvement in near-final height.

Should Skeletal Maturation Be Manipulated for Extra Height Gain?

Skeletal maturation can be delayed by reducing the exposure to estrogens, either by halting pubertal development through administering a GnRH analogue (GnRHa), or by blocking the conversion of androgens to estrogens through an aromatase inhibitor (AI). These agents have been investigated in children with growth disorders (off-label), either alone or in combination with recombinant human growth hormone (rhGH). GnRHa is effective in attaining a normal adult height (AH) in the treatment of children with central precocious puberty, but its effect in short children with normal timing of puberty is equivocal. If rhGH-treated children with growth hormone deficiency or those who were born small-for-gestational age are still short at pubertal onset, co-treatment with a GnRHa for 2-3 years increases AH. A similar effect was seen by adding rhGH to GnRHa treatment of children with central precocious puberty with a poor AH prediction and by adding rhGH plus GnRHa to children with congenital adrenal hyperplasia with a poor predicted adult height on conventional treatment with gluco- and mineralocorticoids. In girls with idiopathic short stature and relatively early puberty, rhGH plus GnRHa increases AH. Administration of letrozole to boys with constitutional delay of growth puberty may increase AH, and rhGH plus anastrozole may increase AH in boys with growth hormone deficiency or idiopathic short stature, but the lack of data on attained AH and potential selective loss-of-follow-up in several studies precludes firm conclusions. GnRHas appear to have a good overall safety profile, while for aromatase inhibitors conflicting data have been reported.

Pubertal development in children with chronic kidney disease

Impairment of pubertal growth and sexual maturation resulting in reduced adult height is an significant complication in children suffering from chronic kidney disease (CKD). Delayed puberty and reduced pubertal growth are most pronounced in children with pre-existing severe stunting before puberty, requiring long-term dialysis treatment, and in transplanted children with poor graft function and high glucocorticoid exposure. In pre-dialysis patients, therapeutic measures to improve pubertal growth are limited and mainly based on the preservation of renal function and the use of growth hormone treatment. In patients with end-stage CKD, early kidney transplantation with steroid withdrawal within 6 months of renal transplantation allows for normal pubertal development in the majority of patients. This review focuses on the underlying pathophysiology and strategies for improving height and development in these patients.