M. T. Pacitti

Clinical usefulness of serum tartrate-resistant acid phosphatase activity determination to evaluate bone turnover

The study was carried out to evaluate the clinical validity and usefulness of serum tartrate-resistant acid phosphatase (TRAP) activity determined using an improved spectrophotometric assay. Enzyme activity was measured in 84 normal subjects and in 109 patients with common metabolic bone diseases. Mean values of serum TRAP activity in male subjects (n = 19; 10.4 +/- 2.15 U l-1) were not significantly different from those found in female subjects (n = 65; 10.8 +/- 1.8 U l-1). In the latter group mean values were significantly raised in post-menopausal subjects (10.5 +/- 2.0 U l-1; p less than 0.01) compared with mean values in pre-menopausal women (8.45 +/- 1.8 U l-1). We found a significant inverse correlation between serum TRAP activity values and bone mineral density (BMD) measured both at an ultradistal radial point (n = 33, r = -0.506; p less than 0.01), and at the lumbar spine (n = 57, r = -0.261; p less than 0.05). Mean serum TRAP activity values in patients with metabolic bone diseases were: primary hyperparathyroidism, n = 30: 14.2 +/- 4.89 U l-1, p less than 0.001 vs normal subjects; chronic maintenance haemodialysis, n = 19: 17.4 +/- 6.7, p less than 0.001; metastatic cancer, n = 13: 21.2 +/- 6.3, p less than 0.001; post-surgical hypoparathyroidism, n = 10: 9.9 +/- 1.8, NS; involutional osteoporosis, n = 20: 12.5 +/- 2.3 p less than 0.001; Pagets disease, n = 10: 16.8 +/- 3.5, p less than 0.001; osteomalacia, n = 7: 19.5 +/- 3.31, p less than 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)

Tartrate-resistant acid phosphate activity as osteoclastic marker : Sensitivity of cytochemical assessment and serum assay in comparison with standardized osteoclast histomorphometry

Tartrate-resistant acid phosphatase (TRAP) activity is regarded as an important cytochemical marker of osteoclasts; its concentration in serum is utilized as a biochemical marker of osteoclast function and degree of bone resorption. This study was carried out to assess the sensitivity of TRAP activity both as a cytochemical marker in histological sections and as a biochemical marker in serum in comparison with the standardized histomorphometric variables of osteoclasts. To this end we investigated 24 patients (21 women, 3 men; 60±17 years of age) affected with various metabolic bone diseases. Osteoclast surface (OcS/BS) and osteoclast number (OcN/BS) were evaluated by standardized histomorphometry in iliac crest biopsies. On the basis of TRAP cytochemical activity, TRAP-positive osteoclast surface (TRAP+OcS/BS) and number (TRAP+OcN/BS) were measured. TRAP-positive cells adjacent to bone and showing one nucleus or no nuclei at all in the plane of section were included in the counts as osteoclasts. Serum TRAP activity was determined by spectrophotometric assay. Values of OcS/BS and OcN/BS were much lower than those of TRAP+OcS/BS (−50%) and TRAP+OcN/BS (−60%), respectively. Correlations between OcS/BS and TRAP+OcS/BS, and between OcN/BS and TRAP+OcN/BS, were highly significant. Serum TRAP was significantly correlated with OcS/BS, OcN/BS, and TRAP+OcN/BS. These correlations, however, were rather low. Moreover, serum TRAP did not correlate with TRAP+OcS/BS. From these results, the conclusion can be drawn that while TRAP activity is confirmed as a valid cytochemical marker for identification of osteoclasts, serum TRAP activity is an osteoclastic marker of weak sensitivity. This may be due to known factors, such as synthesis of the enzyme not being unique to osteoclasts, enzyme instability, and the presence of inhibitors in serum. Mononucleated osteoclasts do not significantly influence the serum enzyme levels.

Effect of estrogen deficiency on IGF-I plasma levels: Relationship with bone mineral density in perimenopausal women

SummaryBone tissue is a source of growth factors; among them, insulin-like growth factor I (IGF-I) is probably an important local regulator of bone formation. This study has been carried out in order to assess the effects of natural menopause on plasma concentrations of IGF-I in the first 6 years after the cessation of gonadal function independent of age. We also examined the relationship between plasma IGF-1 levels and bone mineral density (BMD) measured at the lumbar spine (LS), at the ultradistal radius (UDR), and at the junction of the distal and middle thirds of the radius (MR). Sixty-seven healthy nonobese women, aged 45–55, were studied (premenopausal n = 21; postmenopausal n = 46, from 1 to 6 years since menopause). Plasma IGF-I levels were measured by RIA, after acid-ethanol extraction. BMD of the forearm was measured by dual-photon densitometer and BMD of the LS was assessed by quantitative digital radiography. Mean values of IGF-I plasma levels were significantly reduced in postmenopausal women compared to the premenopausal group. Menopausal duration did not influence IGF-I plasma levels in postmenopausal women. We also found a positive correlation between IGF-I levels and BMD measured at MR both in pre- and postmenopausal women, while a correlation with LS and UDR-BMD was found only in fertile subjects. The results show that IGF-I plasma levels decrease immediately after menopause, since significantly lower levels are reached in the first years. The correlations found between plasma IGF-I levels and BMD suggest a possible role of reduced IGF-I in bone loss at particular skeletal sites.

Serum ionized calcium, parathyroid hormone and related variables: effect of age and sex.

This study was carried out in order to determine interrelationships of age and sex on parameters within the parathyroid endocrine system in healthy men and women. One hundred and fifteen normal subjects (70 females and 45 males) subdivided into three groups aged 25-35, 45-55 and 65-75 years were studied. Female subjects aged between 45 and 55 were further subdivided into two age-matched groups in relation to gonadal functional status. Serum intact parathyroid hormone (PTH) concentrations were measured using a two-site immunoradiometric assay. We found that there was a significant decrease of serum ionized calcium with ageing only in men (r = -0.666, P < 0.001) and a significant increase of serum PTH with age in both men (r = 0.488, P < 0.001) and women (r = 0.279, P < 0.019). A significant inverse correlation was found between serum ionized calcium and PTH in male subjects (r = -0.661, P < 0.001) and in fertile females (r = -0.353, P < 0.037) but not in postmenopausal women or in the entire female population. Furthermore, we found a significant decline of serum phosphate (r = -0.484, P < 0.001) and TmP/GFR (r = -0.492, P < 0.001) with advancing age in men, but not in women. We believe that the decrease of serum ionized calcium, as a likely consequence of the physiological reduction of intestinal calcium absorption, is the pivotal factor responsible for the increased PTH levels we observed with advancing age. The phenomenon is clear in men and in premenopausal women, but is masked in the female sex at menopause by the effects of a shortage of oestrogen on the calcium-phosphorus metabolism. These may also be responsible for the differences observed between the two sexes as far as phosphate metabolism is concerned. In conclusion, this study has, for the first time, taken relationships between serum ionized calcium and PTH, over a wide age range, into consideration. The results obtained show a marked difference of serum ionized calcium values between sexes with ageing, while serum parathyroid hormone levels increase in both men and women. Important differences also exist, as far as phosphate metabolism is concerned, between males and females.

Trabecular bone mineral density in primary hyperparathyroidism : relationship to clinical presentation and biomarkers of skeletal turnover

This study was carried out in order to investigate the entity of trabecular bone involvement in 62 patients with primary hyperparathyroidism (PHPT). Bone mineral density (BMD) was measured in all patients at the ultradistal radius (UDR) of the non-dominant arm by a dual photon densitometer and also at the lumbar spine (L) in 40 of the patients by means of quantitative dual energy radiography. Mean Z score values of UDR-BMD (-2.4 +/- 0.4) and L-BMD (-3.5 +/- 0.2) in patients with the skeletal variety of the disease (n = 6) were significantly reduced in respect to values of both asymptomatic (n = 31) and kidney stone patients (n = 25). As far as the comparison between the two sites of trabecular bone mass measurement in each hyperparathyroid subgroup of patients was concerned, a significant difference (P < 0.05) was found in patients with skeletal manifestations of the disease. Either serum total alkaline phosphatase activity, or osteocalcin and the 24-h hydroxyproline/creatinine ratio were significantly inversely related to the entity of bone mass evaluated at these two sites. Z score changes following surgery in 14 patients showed a positive trend in 13 of them at L compared to 7 out of 14 at UDR (P < 0.036 by chi square analysis). There was a very good inverse correlation between basal Z score values and the changes following surgery at the L (r = -0.851; P < 0.001) but not at the UDR. Our results demonstrate firstly that, in PHPT skeletal sites with almost similar composition of trabecular bone are differently involved in patients with more severe skeletal damage and that different skeletal sites may be divergently affected by the cessation of parathyroid gland hyperfunction.

Annual skeletal balance and metabolic bone marker changes in healthy early postmenopausal women: results of a prospective study

The aim of this study was to establish the duration and annual rate of menopause-related bone loss and to investigate the relationship between bone turnover and bone loss in early healthy postmenopausal women. The rate of change in bone mineral density (BMD) at the lumbar spine and in bone turnover was measured twice at the exact interval of 12 months by dual-energy X-ray absorptiometry (DXA) and by the determination of plasma alkaline phosphatase levels (ALP) and fasting urinary hydroxyproline/creatinine ratio (OHPr/Cr), respectively, in 123 healthy premenopausal and postmenopausal women 45-60 years of age. The subjects were divided into nine groups according to their menstrual status and years since menopause (YSM). Annual bone loss at the lumbar spine of women who were menopausal for 1, 2, 3, 4, and 5 years was -2.62 +/- 0.37 (95% confidence interval -3.66, -1.58), -3.87 +/- 0.96 (-6.02, -1.73), -2.50 +/- 0. 37 (-3.29, -1.70), -2.86 +/- 0.73 (-4.44, -1.27), and -1.54 +/- 0.41 (-2.42, -0.66), respectively, and was significantly less than zero. But, the annual bone loss of women who were premenopausal or menopausal for 6, 7, and 8 years was -0.76 +/- 0.60 (-2.04, +0.53), -1.16 +/- 0.68 (-2.61, +0.29), 0.24 +/- 0.48 (-0.78, +1.26), and 0. 16 +/- 0.63 (-1.18, -1.49), respectively, and was not significantly different from zero. These results demonstrate that the early hormone-dependent bone loss commences in the first year after menopause and is arrested within 6 years after the onset of menopause. The overall bone loss for this phase is estimated to be approximately 15%. Annual change in ALP and OHPr/Cr seems to indicate that bone resorption prevails on bone formation in the first 2 YSM, whereas osteoblastic activity relatively prevails from YSM 3 to YSM 5, which explains the progressive repairing of the imbalance between bone resorption and formation.

Gender Differences in Serum Markers of Bone Resorption in Healthy Subjects and Patients with Disorders Affecting Bone

Abstract: To assess how two different serum markers of bone resorption may reflect changes in bone turnover, we compared age- and sex-related changes in serum C-terminal telopeptide of type I collagen (βCTx) and tartrate-resistant acid phosphatase activity (TRAP) in 136 healthy men and 184 normal women. Serum levels of the two markers were also assessed in several groups of patients of both sexes presenting with the most common metabolic and endocrine bone diseases: established osteoporosis (n= 77), primary hyperparathyroidism (n= 44), glucocorticoid excess (n= 17), chronic renal failure (n= 39), active Paget’s disease of bone (n= 5), humoral hypercalcemia of malignancy (n = 3), osteomalacia (n= 3), hyperthyroidism (n= 10), post-surgical hypoparathyroidism (n= 10), acromegaly (active disease, n= 8) and Cushing’s syndrome (n= 10). In men the regression of βCTx with age showed an initial decrease in bone resorption followed by an increase thereafter, starting from the sixth decade of life. No age-related change in serum TRAP activity was observed. In women, by contrast, a slight but significant linear correlation of both serum βCTx and TRAP with age (r= 0.223, p<0.003 and r= 0.333, p<0.0001, respectively) was found, the two markers being positively correlated (r= 0.238, p<0.002). In each class of patients the mean Z-scores of βCTx were significantly higher than those of TRAP activity. Moreover, compared with normal subjects, serum βCTx seems to be characterized by a superior sensitivity relative to TRAP measurement, at least in the disorders studied.

Quantitative ultrasound assessment of bone in patients with primary hyperparathyroidism

Quantitative ultrasound measurements were done in a group of 26 patients (4 males and 22 females, aged 55.4 ±14.2 years) with primary hyperparathyroidism, and the results were compared with bone mineral density (BMD) carried out at various skeletal sites. Speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness were measured with the Achilles ultrasound bone densitometer (Lunar Corp., Madison, WI). Mean ± SD values of SOS, BUA and stiffness in patients with primary hyperparathyroidism were 1522±38 m/seconds, 111±16 dB/MHz, and 80.4±19.8%, respectively. There were significant differences of mean T-score BUA values (-0.63±1.11) compared with corresponding T-score BMD values found at ultradistal (-1.85±1.73, P<0.01), proximal radius (-2.40±2.13, P<0.001), and total femoral (-1.60±1.32, P<0.001) sites. Correlation coefficients between both SOS and BUA values with BMD measurements at specific skeletal sites varied, but stiffness correlated moderately (0.6–0.9) with BMD. Our data strongly indicate that in patients with primary hyperparathyroidism, bone structure of some skeletal sites, as evaluated by BUA measurement, is compromised to a lesser extent than BMD. In this respect it is interesting to note the lack of significant differences (in terms of mean T-score values) in the comparison of two sites of mostly trabecular composition, that is, the lumbar level (-1.17±1.54) and the femoral Wards triangle (-0.99±1.25). Our results seem to lend further support to the hypothesis that in primary hyperparathyroidism cancellous bone architecture might be preferentially maintained. Quantitative ultrasound techniques appear to complement, and could possibly substitute for, existing bone densitometry examinations.

Bone turnover and its relationship with bone mineral density in pre- and postmenopausal women with or without fractures

OBJECTIVE This work was carried out in order to investigate possible relationships between bone turnover rate, as evaluated by bone biomarkers and skeletal mass, as evaluated by bone mineral density (BMD). METHOD Fifty-eight normal women and 30 female patients with osteoporotic fractures were enrolled. Three groups were defined: (1) fertile subjects (n = 24), mean age 33.7 +/- 8.1 years; (2) postmenopausal women (n = 32, including 11 patients with fractures) whose BMD values, in terms of T score, were less than -2.5 S.D. below the young adult mean obtained in our laboratory (mean age 61.7 +/- 7.9 years; and years since menopause (ysm), 12.6 +/- 8.3); (3) postmenopausal women (n = 32, including 19 patients with fractures) whose BMD values in terms of T score, were below -2.5 S.D. (mean age 62.9 +/- 8.6 years; and ysm 15.9 +/- 9.0). Groups II and III characterised, by inclusion criteria, by significant different mean BMD values, were similar as far as chronological and menopausal age were considered. Metabolic tests included a short urine collection to determine calcium, hydroxyproline, cross-linked N-telopeptides of type I collagen (NTx) and creatinine (Cr); half-way through this collection, a blood sample was taken for the measurement of total alkaline phosphatase activity (ALP) and tartrate-resistant acid phosphatase activity (TRAP). BMD at lumbar spine was evaluated. RESULTS There were significant differences amongst the three groups in mean ALP (P < 0.001, by analysis of variance) TRAP (P < 0.006) and NTx/Cr (P < 0.001) values, but not as far as mean values of calcium/Cr or hydroxyproline/Cr ratios were concerned. Considering the group as a whole, there were significant inverse correlations between NTx/Cr, ALP, TRAP and BMD controlling for both age (r = -0.392, P < 0.001; r = -0.447, P < 0.001 and r = -0.327, P < 0.002, respectively) and ysm (r = -0.374, P < 0.001; r = -0.474, P < 0.001 and r = -0.333, P < 0.002). CONCLUSIONS Our results indicate, that, even after controlling for both ageing and oestrogen status, there is an inverse relationship between bone mass (that at a given time represents the balance of all previous metabolic events) and a biochemical marker (which reflects bone turnover at the time of examination). These findings are in line with the belief that increased bone turnover should be regarded as a risk factor for osteoporosis. Furthermore, our results indicate that, unless there is no increase of hepatic isozyme, total ALP still maintains a possible role as a first analysis to evaluate bone turnover before requesting markers with greater specificity, sensitivity but also more expensive and whose analysis is sometimes time-consuming.

Reduced serum levels of car☐y-terminal propeptide of human type I procollagen in a family with type I-A osteogenesis imperfecta

We measured serum levels of total alkaline phosphatase activity, osteocalcin, carboxy-terminal propeptide of human type I procollagen (PICP), tartrate-resistant acid phosphatase activity (TRAP), and the fasting urinary hydroxyproline/creatinine ratio (OHPr/Cr) in seven affected members (four men, three women; age, 43.3 +/- 16.6 years [mean +/- SD]) of a family with clinically diagnosed type I-A osteogenesis imperfecta (OI) and in eight (five men, three women) normal age-matched (38.2 +/- 10.3) relatives. Three boys with OI and three normal girls of the same family were also studied, although they were excluded from statistical analysis. Bone mineral density was also determined at four different skeletal sites. Serum levels of PICP were measured with a radioimmunoassay (Farmos Diagnostica, Turku, Finland). There were no significant differences in mean values of the biomarkers studied between OI patients and normal relatives, with the only exception being serum levels of PICP (35 +/- 7.5 v 219 +/- 107.5 micrograms/L, P < .001). A significant reduction of BMD was found in OI patients compared with normal relatives at the lumbar (L) spine (680 +/- 61 v 1,128 +/- 92 mg/cm2, P < .001), at the ultradistal radius ([UDR] 323 +/- 85 v 458 +/- 76, P < .006), at the femoral neck ([F] 494 +/- 140 v 791 +/- 104, P < .001), and at the junction of the distal and middle third of the radius ([MR] 639 +/- 71 v 717 +/- 52, P < .029).(ABSTRACT TRUNCATED AT 250 WORDS)