Variations of some plasma components after closed fractures

Role of common biochemical markers for the assessment of fracture union

The progress of fracture union requires close monitoring. Whereas, clinical examination and radiographic studies assess the outcome, biochemical markers like serum alkaline phosphatase and urinary hydroxyproline reflect the actual status of bone resorption and bone formation over a short time frame. 36 patients of long bone fracture were randomly allocated for the study. When the patient reported to the Department of Orthopedics after fracture, serum and urinary samples were collected and X-ray of the affected part were taken. Subsequent samples were collected and X-ray taken just after management (either operative or conservative), after 3rd, 5th, 8th and 12th week, respectively after onset of fracture. According to the course of callus formation the patients were divided into two groups that progressed to proper union or malunion. The levels of serum alkaline phosphatase, urinary total and free hydroxyproline levels were measured and statistically analysed and compared. A statistically significant positive correlation between total urinary hydroxyproline excretion and serum alkaline phosphatase indicate progress towards satisfactory union. Thus, serial monitoring of biochemical markers of bone turnover can be used as an adjunct to clinical and radiological evidence of fracture healing.

Systemic regulation of distraction osteogenesis: a cascade of biochemical factors

This study investigates the systemic biochemical regulation of fracture healing in distraction osteogenesis compared with rigid osteotomy in a prospective in vivo study in humans. To further clarify the influence of mechanical strain on the regulation of bone formation, bone growth factors (insulin-like growth factor [IGF] I, IGF binding protein [IGFBP] 3, transforming growth factor [TGF] beta1, and basic FGF [bFGF]), bone matrix degrading enzymes (matrix-metalloproteinases [MMPs] 1, 2, and 3), human growth hormone (hGH), and bone formation markers (ALP, bone-specific ALP [BAP], and osteocalcin [OC]) have been analyzed in serum samples from 10 patients in each group pre- and postoperatively. In the distraction group, a significant postoperative increase in MMP-1, bFGF, ALP, and BAP could be observed during the lengthening and the consolidation period when compared with the baseline levels. Osteotomy fracture healing without the traction stimulus failed to induce a corresponding increase in these factors. In addition, comparison of both groups revealed a significantly higher increase in TGF-beta1, IGF-I, IGFBP-3, and hGH in the lengthening group during the distraction period, indicating key regulatory functions in mechanotransduction. The time courses of changes in MMP-1, bone growth factors (TGF-beta1 and bFGF), and hGH, respectively, correlated significantly during the lengthening phase, indicating common regulatory pathways for these factors in distraction osteogenesis. Significant correlation between the osteoblastic marker BAP, TGF-beta1, and bFGF suggests strain-activated osteoblastic cells as a major source of systemically increased bone growth factors during callus distraction. The systemic increase in bFGF and MMP-1 might reflect an increased local stimulation of angiogenesis during distraction osteogenesis.

Bilateral tibial marrow ablation in rats induces a rapid hypercalcemia arising from extratibial bone resorption inhibitable by methylprednisolone or deflazacort

The goals of this study were to quantitate biochemical markers of bone metabolism on days 1-15 after bilateral tibial marrow ablation surgery in young adult rats and to determine the effect of a single dose of methylprednisolone (2 mg/kg) or deflazacort (2.5 mg/kg) given at the time of ablation. Unexpectedly, serum calcium levels rose to a maximum of 15.9 mg/dl on day 7 after marrow ablation and remained above normal through day 15. This increase was blocked by a single intramedullary injection of methylprednisolone or deflazacort immediately following ablation; however, the fact that both drugs produced a characteristic rapid 3- to 10-fold increase in the serum alpha 2-macroglobulin level demonstrates that the drugs rapidly reached the circulation. Both methylprednisolone and deflazacort also inhibited intramedullary deposition of collagen by 40-60% on day 7, a time near which operated control animals achieved maximal accumulation of new bone in this model. Histological comparisons among the three experimental groups were largely consistent with biochemical results. The urinary hydroxyproline/creatine ratio for the operated control group doubled on day 3 and then returned to presurgical levels on day 7 and later. The timing and size of the hydroxyproline/creatinine peak, as well as the fact that the intratibial osteoclastic response peaks on days 8-10 after ablation, suggests it results from extratibial bone resorption induced by marrow ablation. Consistent with this rationale, urinary calcium excretion in operated controls rose 9-fold from day 0 to day 3 and appeared to plateau over the period from day 3 to day 9, before returning to a near presurgical level on day 15. Elevated excretion of calcium noted on days 9-15 in deflazacort-treated animals, which occurs in the absence of a detectable increase in resorption marker hydroxyproline, may however be due to the known action of glucocorticoids in increasing kidney filtration of calcium. In summary, this is the first report to show that bilateral tibial marrow ablation in rats causes a rapid hypercalcemia and calciuria which is accompanied initially by a peak of bone resorption marker urinary hydroxyproline. We speculate that the source of calcium and hydroxyproline is extratibial osteoclastic bone resorption induced by circulating cytokines whose release from ablated tibias or osteoclastogenic action is inhibitable by methylprednisolone and deflazacort.

Hypercalcitoninemia and inappropriate calciuria in the acute trauma patient

PURPOSE

This study was undertaken to determine the role of calcium-regulatory hormones (calcitonin [CT], parathyroid hormone [PTH], and vitamin D analogs) during the first 48 hours after acute trauma.

METHODS

Eleven acutely traumatized patients admitted to the shock-trauma intensive care unit (STICU) in a tertiary care teaching hospital were enrolled. Eleven same-day elective surgery patients served as the control group. Levels of ionized calcium (Ca2+), total calcium, magnesium, phosphate, CT, PTH, vitamin D analogs, electrolyte supplementation, and renal electrolyte loss were recorded during the first 48 hours after admission to the STICU. Control-group measurements consisted of Ca2+ and CT.

RESULTS

At admission, 91% of the patients had ionized hypocalcemia (1.04 +/- 0.10 mmol/L). Ca2+ levels increased significantly over time (1.13 +/- 0.08 at 24 hours; 1.16 +/- 0.07 at 48 hours) but remained below the control-group value (1.28 +/- 0.05; P < .05) despite supplementation. Ninety-one percent of the patients had increased CT values at admission, 91% at 24 hours, and 78% at 48 hours. Median CT values in the trauma patients were higher throughout the study than in the control group (P < .05). Urinary calcium loss in the trauma patients was within the normal range. PTH and vitamin D analog values were within the normal range throughout the study. Multiple regression analysis did not show any significant correlation between electrolytes and hormone or protein concentrations.

CONCLUSIONS

Acute trauma patients have ionized hypocalcemia associated with inappropriate urinary calcium loss, increased CT levels, and normal PTH and vitamin D analog values. We believe the degree of calciuria we observed was inappropriate in the context of ionized hypocalcemia. The cause of these increased CT levels is unclear. Our results suggest that Ca(2+)-regulatory mechanisms may be disrupted in the acute trauma patient.

Serum intact parathyroid hormone levels in elderly Chinese females with hip fracture

Serum intact parathyroid hormone (PTH), 25 hydroxyvitamin D(25OHD), 1,25 dihydroxyvitamin D (1,25(OH)2D), albumin, and ionized calcium were measured in 61 Chinese female patients with hip fracture and 61 control subjects. Hip fracture patients had low albumin, ionized calcium, and 250HD levels. Serum PTH and 1,25(OH)2D values were not different between the two groups. We conclude that although 250HD level in hip fracture patients is low, there is no evidence of secondary hyperparathyroidism, suggesting that the low 250HD levels may be a secondary phenomenon in response to the fracture.

Osteomalacia and osteoporosis in femoral neck fracture

Iliac crest bone histomorphometry, plasma and urine biochemistry and clinical history were examined in 78 unselected patients (68 women, 10 men) at the time of femoral fracture. Histological abnormalities occurred in 56 of the 78 biopsies. The commonest of these was a low bone volume of less than 15% which, irrespective of other abnormal histological features, was present in 37 of the biopsies. On the basis of the histomorphometry, patients could be classified into four main groups. Normal histomorphometry (bone volume greater than 15%, osteoid surfaces less than 24%, mineralising surface greater than 60%) was present in 22 patients, 23 had osteoporosis as the only abnormality (bone volume less than 15%, osteoid surface less than 24%, mineralising surface greater than 60%), nine had osteomalacia (osteoid surfaces greater than 24%, mineralising surface less than 60%, osteoid width greater than 13 microns) and 13 had decreased mineralising surfaces. Of the remainder, five had increased osteoid surface and six had insufficient osteoid to assess mineralising surface. Plasma and urine biochemistry in the four groups showed that, compared to age-matched controls, all groups had reduced plasma albumin. In comparison to the group with normal histomorphometry, patients with osteoporosis had a higher plasma calcium (P less than 0.01), tubular reabsorption of calcium (P less than 0.05) and plasma vitamin D binding protein (P less than 0.01); patients with osteomalacia had a higher plasma creatinine (P less than 0.02) and parathyroid hormone (P less than 0.02) and lower plasma 24,25-dihydroxyvitamin D (P less than 0.02), urinary calcium/creatinine ratio (P less than 0.02) and tubular reabsorption of phosphate (P less than 0.02). The biochemistry in patients with decreased mineralising surface was no different from patients with a normal biopsy. The prevalence of both osteoporosis and osteomalacia increased with age and, in subjects over the age of 90, osteoporosis occurred in 71% of patients and osteomalacia occurred in 29% of patients. The osteomalacic group were significantly older than the other three groups (P less than 0.05). The histomorphometry did not relate to the site of fracture (subcapital or intertrochanteric). A history of stroke, gastrectomy, rheumatoid arthritis, steroid treatment, thyroid disease, alcohol abuse and anti-convulsant therapy was present in patients with femoral fracture but did not relate to any particular histomorphometric classification.

Osteogenic response to marrow aspiration: increased serum osteocalcin and alkaline phosphatase in human bone marrow donors

It has been shown recently in experimental animals that regeneration of bone marrow after ablation is associated with enhanced osteogenic growth factor activity and a systemic increase in bone formation. To assess the possible occurrence of a similar phenomenon in humans, serum markers of bone formation, osteocalcin and alkaline phosphatase, were measured in marrow donors before the aspiration of large amounts of iliac marrow and 1 day to 5 weeks thereafter. Both osteocalcin and alkaline phosphatase showed significant increases, with peak values 1-3 and 2-4 weeks postaspiration, respectively. The absolute maximal increase in osteocalcin was significantly higher in adolescent and child donors than in adults. When evaluated together with studies on systemic changes during fracture healing and marrow regeneration, these findings suggest that marrow aspiration in humans evokes a systemic osteogenic response.

Indices of calcium metabolism in women with hip fractures

We have assessed indices of calcium metabolism in 41 women with hip fractures and compared them with two elderly control groups. The women with hip fractures had lower serum concentrations of albumin, 25-hydroxyvitamin D and osteocalcin than the controls. Serum concentrations of calcium, alkaline phosphatase and parathyroid hormone, as well as urinary hydroxyproline/creatinine ratios were similar in the three groups of women. The small reduction in serum osteocalcin concentration in fracture patients is consistent with the hypothesis that reduced osteoblast function may contribute to the osteoporosis which results in hip fracture.

Serum osteocalcin and total alkaline phosphatase levels as prognostic indicators in tibial shaft fractures

Serum samples were obtained periodically from 50 adult patients with closed tibial shaft fractures. Total alkaline phosphatase activity was measured in all cases and osteocalcin activity was measured in 14 patients. Fractures produced by high-energy violence generally had lower values of osteocalcin activity. This could be due to depressed circulating vitamin K levels throughout the healing period in the former fractures. In addition, normally uniting fractures had generally higher values of osteocalcin activity compared with fractures exhibiting delayed union. This indicates depressed osteoblastic activity in slowly healing fractures. The results suggest that measurement of osteocalcin activity after fracture could provide a useful prognostic indicator. By contrast, total serum alkaline phosphatase activity was not significantly different between the injury groups and between the healing groups.

The effect of trauma on serum concentrations of vitamin D metabolites in patients with hip fracture

In a previous study we observed lower serum concentrations of 25(OH)D, 24,25(OH)2D, and 1,25(OH)2D in patients with hip fracture than in aged control subjects. In order to evaluate the effect of trauma on vitamin D metabolite levels, we measured serum concentrations of vitamin D binding protein (DBP) in 118 patients with hip fracture and 71 aged control subjects. Serum DBP was lower in the patients than in the controls (mean +/- SD 315 +/- 60 vs 371 +/- 44 mg/l, P less than 0.001). Serum DBP correlated positively with serum total protein, albumin, alpha 2-globulin, and the vitamin D metabolite levels in the patients. When correcting for differences in serum DBP, serum 25(OH)D and 24,25(OH)2D still were significantly lower in patients than in controls, whereas serum 1,25(OH)2D was not. The free 1,25(OH)2D index (10(5) x molar ratio 1,25(OH)2D/DBP) was lower in patients than in controls, but the level of significance was marginal. This difference was not significant when patients and controls with impairment of renal function were excluded. It is concluded that the difference in serum 25(OH)D and 24,25(OH)2D between patients and controls is largely preexistent. However, the lower serum 1,25(OH)2D in the patients is mainly caused by the trauma. The free 1,25(OH)2D concentrations are almost similar in the two groups when renal function is normal.

Parathyroid hormone secretion after operative bone trauma

Skeletal trauma in man (operations for scolioses and femoral shortening) results in a significant increase in parathyroid hormone secretion beginning the day after the operation and lasting for more than 1 week. A concurrent decrease in serum calcium, dependent on the postoperative lowering of serum albumin, was also observed.