Las adolescentes no pierden densidad mineral ósea en el posparto: estudio comparativo con adultas / Adolescents do not lose bone mineral density postpartum: comparative study with adult women

OBJETIVO: Analizar el patrón de la densidad mineral ósea (DMO), calcio y estradiol séricos, consumo de calcio, índice de masa corporal (IMC) y lactancia en adolescentes y adultas a 15, 90 y 365 días posparto (dpp). MATERIAL Y MÉTODOS: Cohorte prospectivo en 33 adolescentes y 39 adultas con evaluación antropométrica, dietética y ósea en L2-L4 y cuello de fémur; bioquímica con estradiol y calcio séricos. RESULTADOS: Las adolescentes aumentaron de los 15 a los 365 dpp 16 por ciento su DMO de L2-L4, las adultas 3 por ciento. La edad se asoció a este cambio (β=13.779, EE=3.5, p=0.001); la lactancia no se asoció (β=-0.705, EE=0.647, p=0.283). Las adultas presentaron mayor DMO de L2-L4 a 15, 90 y 365 dpp respectivamente (1.151vs 0.978g/cm², 1.195vs1.070g/cm², 1.195vs1.123g/cm², p<0.003). CONCLUSIONES: Las adolescentes incrementaron su DMO tres veces más que las adultas. El cambio en la DMO fue dependiente de la edad e independiente de la práctica de lactancia.

OBJECTIVE: To analyze the pattern of bone mineral density (BMD), serum concentrations of estradiol and calcium levels, dietary calcium, body mass index (BMI), and lactation in adolescents and adult women at 15, 90, and 365 postpartum days (ppd). MATERIAL AND METHODS: A prospective cohort study was conducted of 33 adolescents and 39 adult women. Anthropometric and dietetic evaluations were performed, as well as evaluations of bone mineral density in L2-L4 and femur neck. Estradiol concentrations and calcium serum levels were determined. RESULTS: L2-L4 BMD increased by 16 percent in adolescents, and 3 percent in adult women from day 15 to 365 ppd. While age was associated with this change (β=13.779, EE=3.5, p=0.001), lactation was not (β=-0.705, EE=0.647, p=0.283). The adult women had a higher L2-L4 BMD at 15, 90, and 635 ppd (1.151 vs 0.978g/cm², 1.195 vs 1.070g/cm², 1.195 vs 1.123g/cm², respectively) (p<0.003). CONCLUSIONS: Adolescents' BMD increased three times more than that of adult women. For all women, BMD was dependent of age and independent of lactation.

Recambio óseo en nodrizas adolescentes: evaluación al término de la gestación, lactancia y postdestete / Bone turnover in lactating teenagers: assessment at the end of pregnancy during and after the breast feeding period

Background: There is paucity of information about bone metabolism during pregnancy or breast feeding in teenagers. Aim: To study bone turnover at the end of pregnancy and during breast feeding in teenagers and correlate it with environmental, hormonal or nutritional variables. Subjects and methods: Thirty teenagers during their breast feeding period after a first pregnancy and 30 nulliparous girls matched for age, age of menarche and body mass index were assessed three weeks after delivery (period 1), at six months of breast feeding (period 2) and one year after the lactating period (period 3). Calcium intake and plasma calcium, phosphorus, alkaline phosphatases, parathormone, estradiol and prolactin were measured. Calcium, creatinine and hydroxyproline were also measured in a morning urine sample. Results: Lactating and control girls were aged 16.3ñ0.8 and 16.1ñ0.7 years old respectively. Calcium intake in lactating and control girls was 798ñ421 and 640ñ346 g/day respectively in period 1, 612ñ352 and 592ñ309 mg/day in period 2 and 495ñ180 and 456ñ157 g/day in period 3. During periods 1 and 2, lactating girls had higher alkaline phosphatases (161ñ37 compared to 119ñ28 U/l and 149ñ37 compared to 106ñ23 U/l), parathormone (4.3ñ2.6 compared to 2.8ñ0.8 ng/dl and 3.6ñ1.6 compared to 3.0ñ0.9 ng/dl) and urinary hydroxyproline (95ñ16 compared to 63ñ15 mg/g creatinine and 84ñ19 compared to 59ñ15 mg/g creatinine). No differences were observed in period 3. No correlation between bone turnover variables, body mass index or hormonal parameters, was observed. Conclusions: In teenagers, there is an increase in bone turnover at the end of pregnancy, that persists during the lactating period. These changes are not related to nutritional or hormonal variables