Effect of Puberty on the Relationship between Bone Markers of Turnover and Bone Mineral Density in Turner’s Syndrome

Abstract

It has been suggested that the appropriate timing of puberty is necessary for normal bone mineral acquisition which may not be achieved amongst patients with Turner’s syndrome (TS). The aim of this study was to assess bone mineral density (BMD) and bone turnover in 34 patients with TS (age range 2.2–39.0 years). The areal BMD (aBMD) was determined by dual-energy X-ray absorptiometry, and the volumetric BMD was calculated. Blood and second voided urine samples were taken the morning after an overnight fast for evaluation of the biochemical markers of bone turnover: bone-specific alkaline phosphatase (BAP) and N-telopeptides of type I collagen (NTX), respectively. Both were determined by enzyme-linked immunosorbent assay. The patients were divided into three groups: group 1 (n = 13; prepubertal; age range 2.2–19.0 years), group 2 (n = 10; teenagers; age range 12.4–19.0 years), and group 3 (n = 11; adults; chronological age >20 years). They were also grouped by breast development according to Tanner stage into B1 (n = 12), B2–3 (n = 9), and B4–5 (n = 13). The aBMD was significantly lower in group 1 and was higher at Tanner stages 4 and 5 as compared with patients at Tanner stage 1. The bone turnover markers were significantly higher in group 1 (NTX: p = 0.002; BAP: p = 0.0005) and declined, as puberty progressed. A negative correlation was observed between aBMD and biochemical bone markers at the lumbar spine (NTX: r = –0.54, p = 0.05; BAP: r = –0.44, p = 0.01) and in the whole body (NTX: r = –0.60, p = 0.0008; BAP: r = –0.19, p = 0.002). We conclude that the negative relationships between aBMD and biochemical markers suggest a high bone turnover, mainly in prepubertal patients and that the results observed in relation to aBMD and puberty are imputed to the delayed puberty which occurs amongst TS patients.

Normal Tempo of Bone Formation in Turner Syndrome despite Signs of Accelerated Bone Resorption

“…The relationship between biochemical bone markers, bone density, and endocrine changes of puberty in normal girls are thus not completely understood, and studies in TS are sparse. One study found increased levels of bone formation and resorption mainly in prepubertal girls with TS but no control group was included [17]. With the age distribution in our cohort, we anticipated bone cells to be engaged primarily in modeling processes.…”

“…The combined use of aBMD and biochemical bone markers is helpful in fracture risk assessment in postmenopausal women [15]. However, little is known about the relation of aBMD and also vBMD to bone markers in young TS [1,16,17] as well as to sex hormones and other growth factors [11]. …”

Endocrine diseases, perspectives and care in Turner syndrome

“…In addition, prepubertal estradiol secretion may also play a role in bone mass acquisition during this period. Adolescents girls with TS and spontaneous puberty have bone mineral density (BMD) in the normal range, while in TS girls who underwent induced puberty (48) and young TS patients do not attain peak BMD despite proper HRT and growth hormone therapy (49).…”

“…Bone deficiency is most marked at the femoral neck and seems correlated with serum testosterone and estradiol levels (58).…”

Turner Syndrome: An Update and Review for the Primary Pediatrician

“…24 Sex hormone replacement should be synchronized with GH therapy with continued monitoring for side effects from this therapy as well. 9,34 Conjugated estrogens like Premarin or ethinyl estradiol are the most common form of replacement therapy, while standard lowdose birth control pills are used less often for monthly maintenance. Depending on one's initial height, the desire for reproduction, concerns for osteopenia, osteoporosis or atherosclerosis, GH therapy schedules, and personal preferences, sex hormone replacement regimens, doses, and length of therapy should be determined on an individual basis.…”