Marcadores de formación y resorción ósea y su utilidad para determinar el final del periodo de aposición ósea / Bone formation and resorption markers to evaluate the end of bone apposition

El pico de masa ósea (PMO) se alcanza entre los 20 y 35 años, pero la aposición ósea continúa hasta alcanzar el pico de fortaleza ósea (PFO). Se crea así una ventana entre ambos picos que podría ser evaluada mediante marcadores bioquímicos de recambio óseo, ya que durante dicho período la densidad mineral permanece constante. El objetivo fue determinar el final de la aposición ósea mediante marcadores bioquímicos óseos. Se evaluaron por décadas entre 20 y 49 años de edad 139 sujetos sanos de ambos sexos (69 hombres y 70 mujeres), determinando fosfatasa alcalina ósea (FAO), osteocalcina (OC), propéptido amino terminal del colágeno tipo 1 (P1NP) y telopéptido C-terminal del colágeno tipo 1 (CTX). Los marcadores correlacionan negativamente con la edad (OC: r= -0,3; p<0,01; P1NP: r= -0,4; p< 0,01 y CTX: r= -0,4; p<0,01), exceptuando FAO. En hombres de 20-29 años, P1NP y el CTX fueron significativamente mayores vs. 30-39 años (p<0,05 y p<0,001, respectivamente), y entre 30-39 años vs. de 40-49 años en P1NP y CTX (p<0,05; p<0,001, respectivamente). En mujeres de 20-29 años, P1NP y CTX fueron significativamente mayores vs. 30-39 años (p<0,0001 y p<0,01, respectivamente). Conclusión: los marcadores de remodelado óseo más sensibles y específicos permitirían determinar bioquímicamente el fin de la aposición ósea que se produce entre el PMO y el PFO. Si bien es necesario ampliar el número de sujetos evaluados, los datos que surgen de la presente investigación sentarían las bases para futuros estudios epidemiológicos referidos al fin de la aposición ósea. (AU)

Peak bone mass is achieved between 20-35 years; however bone apposition continues to reach an optimal skeleton strength. The window between peak bone mass and peak bone apposition may be evaluated by biochemical bone turnover markers. The objective of this study was to determine the end of bone apposition through biochemical bone markers in both sexes. A total of 139 subjects (69 men and 70 women) were divided by decades between 20 and 49 years of age. Bone alkaline phosphatase (BAL), osteocalcin (OC), type I collagen propeptide (P1NP) and type I collagen C-terminal telopeptide (CTX) were evaluated. Except BAL, the other bone markers negatively correlated with the age [OC (r= -0.3; p<0.01); P1NP (r= -0.4; p<0.01) and CTX (r= -0.4; p<0.01)]. Regarding men aged 20 to 29 years, P1NP and CTX were significantly higher vs. 30-39 years (p<0.05 y p<0.001, respectively) and. vs. 40-49 years (p<0.05; p<0.001, respectively). In women, the results were similar. Regarding 20-29 years, P1NP and CTX were higher vs. 30-39 years (p<0.001 y p<0.01, respectively). Bone remodeling rate decreases after the third decade, suggesting the end of the apposition period of peak bone mass. Conclusion: The most specific and sensitive bone markers would biochemically determine the end of bone apposition that extends between the peak of bone mass and the peak of bone strength. Although it is necessary to increase the number of subjects evaluated, the data that emerge from the present study would establish the bases for future epidemiological studies referring to the end of bone apposition. (AU)

Chronic idiopathic hyperphosphatasia: normalization of bone turnover with cyclical intravenous pamidronate therapy.

Chronic idiopathic hyperphosphatasia (CIH), or juvenile Paget disease, is a rare disorder characterized by increased bone turnover and progressive enlargement of bones. We report a girl, 6 1/2 years old, with a history of three fractures, short stature, delayed eruption of teeth, and poor hair growth. She had a waddling gait, bone deformities, kyphoscoliosis, hyperlordosis, genu valgum and curvature of her limbs. She also had progressive hearing loss but other cranial nerves were unaffected. Laboratory studies indicated high bone turnover: serum alkaline phosphatase: 4047 IU/l (normal value: 150-550), urinary hydroxyproline: 1205 mg/g creatinine (n.v.: 60-160), and urinary CrossLaps: 4360 microg/mmol creatinine (n.v.: 450-2100). Radiographs demonstrated generalized skeletal involvement with osteoectasia (expansion) of long bones, diffuse sclerosis, cotton wool appearance of the skull, absence of mastoid pneumatization, and crushed dorsal and lumbar vertebrae. Iliac crest biopsy was compatible with CIH. Cyclical intravenous pamidronate (1 mg/kg/day during 3 h, 3 consecutive days at 2- to 3-month intervals) was administered during 2 years with oral calcium 500 mg and vitamin D 1000 IU/day. Oral pamidronate was added after 11 months of i.v. therapy. Treatment-induced remarkable clinical and radiographic improvement with normalization of bone markers of osteoblastic and osteoclastic activity, including bone alkaline phosphatase, urinary hydroxyproline, and urinary CrossLaps.