An infant case of macroprolactinemia with transient idiopathic central precocious puberty

Macroprolactinemia was recognized more than a decade ago as a cause of hyperprolactinemia and the prevalence of macroprolactinemia is thought to be 10%-26% of patients with hyperprolactinemia. However, there are few published reports about macroprolactinemia in childhood. We report a 7-year-and-1-month-old girl with hyperprolactinemia due to macroprolactinemia with the complication of transient idiopathic central precocious puberty (ICPP). At the age of 6 years and 9 months, she was diagnosed with ICPP at another clinic, on the basis of isolated mammary development and increased height velocity with slightly advanced bone age. At that time, the unexpected finding of high PRL level was also observed. Four months later, she was referred to our clinic for persistently high PRL level. At this time, other endocrinological data showed prepubertal stage and we demonstrated macroprolactinemia and the presence of anti-PRL autoantibody. After other causes of hyperprolactinemia such as prolactinoma and stress were ruled out, we finally diagnosed her with hyperprolactinemia due to macroprolactinemia. Because most patients with macroprolactinemia are symptom-free despite hyperprolactinemia and drug therapy would not be indicated, macroprolactinemia should be suspected even in children to avoid unnecessary examinations and treatments.