ESPE Abstracts

Background: Most comprehensive guidelines on tall stature suggest that extremely tall children (defined as height above +3 SDS) should be referred to specialized health care for comprehensive diagnostic work-up. However, currently the etiology of tall stature is poorly characterized and no systematic studies focusing on extreme tall stature exist.

Methods: We identified all subjects with height above +3 SDS after the age of three years from the Helsinki University Hospital district that is subjected to growth monitoring and screening rules. The district covers a population of 1.2 million with a yearly birthrate of approximately 13500. Subjects born prior to 1990 or subjects with missing or erroneous data were excluded. We report the diagnoses underlying extreme tall stature and describe auxological clues and clinical features indicative of underlying growth disorders.

Results: We identified 424 extremely tall subjects that fulfilled all our inclusion criteria. Extreme tall stature was equally frequent in females (n = 214) and males (n = 210). A pathological cause for tall stature (i.e. primary or secondary growth disorder) was diagnosed in 61 patients: in 17% of the girls and 12% of the boys (P = NS). Secondary causes were diagnosed in 42 (10%) patients and the two most frequent secondary diagnoses, premature adrenarche (n = 16) and central precocious puberty (n = 11) were more frequent in girls. Primary causes for tall stature were diagnosed in 19 (4%) patients: Marfan syndrome (n = 10) was the most common primary cause, followed by Sotos syndrome (n = 5). Overall, the most frequent diagnosis was idiopathic tall stature (ITS) diagnosed in 363 (86%) subjects, 141 of whom had a tall parent (parental height above 2 SDS). Features associated with syndromic tall stature (i.e. dysmorphic feature or neurodevelopmental disorder) were noted in almost all patients with a primary cause (95%) and were common among subjects with ITS (29%). The probability of primary growth disorders increased with increasing degree of tall stature. Height SDS cut-off of +3.7 SDS resulted in 81% sensitivity and 63% specificity in detecting a syndromic growth disorder, with a positive likelihood ratio of 2.2 and a negative likelihood ratio of 0.30.

Conclusions: A considerable proportion of extremely tall children have an underlying pathological cause. Syndromic causes were more frequent in subjects with greater height SDS. Clinical features related to syndromic causes of tall stature were surprisingly frequent in subjects with ITS. Our results support comprehensive diagnostic work-up in extremely tall children.