Frequency of biochemical abnormality in elderly with fracture neck of femur

To assess the frequency of abnormal results of bone profile tests including serum calcium, phosphate, alkaline phosphatase and the results of parathyroid hormone in patients with fracture neck of femur. The study includes a group of 100 elderly patients ages 60 years and older with fracture neck of femur


Introduction
Vitamin D deficiency is common in elderly (1) and is thought to be a contributing factor to fall risk via effects on neuromuscular function (2) .In Asians, a raised PTH is a better determinant of histological osteomalacia than 25hydroxyvitamn D and it is more predictive of osteomalacia (3) , and is therefore a better initial test for Asian patients with musculoskeletal symptoms, a reasonable policy is to measure calcium and PTH (4) .It was reported that patients with abnormal routine biochemistry (serum calcium, phosphate and ALP) had a greater increase in PTH than those with normal biochemistry, in other words, abnormal routine biochemistry may point to more advanced bone disease (5) .It is wellestablished that serum PTH concentration varies inversely with absorbed calcium (6) .A functional deficit of Vitamin D would, therefore, be expected to impair calcium absorptive efficiency, leading to a rise in PTH production (7)   .Secondary hyperparathyroidism is associated with increased bone resorption (8) and low bone mass (9) .Bone loss results from an imbalance between the two processes of bone resorption and bone formation (10) .Secondary hyperparathyroidism is one of the determinants of femoral bone loss (11) .It has been suggested that an elevation in PTH is a sensitive pointer to significant hypovitaminosis D (12) .Parathormone is a recognized marker of bone remodeling (13) , and is the principal regulator of calcium homeostasis (14) .A raised PTH usually indicates secondary hyperparathyroidism (unless there is concomitant primary or tertiary hyperparathyroidism) (15) .

Materials and Methods
This study represents a case control study.The study includes 100 elderly pateints ages 60 years or older, The mean ± SD for age (67.91±7.61)(served as a case group), presented with recent fractured neck of femur due to falling from standing height, were selected from orthopedic ward in Al-Jumhoori teaching hospital in Mosul.A control group of 100 healthy elderly person without fracture neck of femur from the same age range, with a mean ± SD for age(65.39±6.25) were selected from patients of the ENT and Ophthalmology departments in the same hospital.Before starting data collection, all participants were informed about the objectives of the study.The subjects selected for the study were free from secondary risk of metabolic bone disease apart from age, genetic and menopause.The subjects of both groups were interviewed and the general information were taken, including name, age, sex, medical history, surgical history, drug history, smoking habits, marital state, number of children (parity), and history of breast feeding.Both groups were referred to the laboratory of Department of Biochemistry/ College of Medicine/ University of Mosul, for measuring serum parathyroid hormone by Enzyme-Linked ImmunoSorbent Assay (ELISA) (16) by a kit supplied from "DGR".Serum calcium measured colorimetrically (17) by a kit supplied from "Biolabo".Corrected [calcium]= measured [calcium]+0.02(40-[albumin]) (18) .Serum phosphate was measured colorimetrically (17) by a kit supplied from "SPINREACT,Spain".Serum albumin was measured by colorimetric determination (19) using a kit from "Biolabo " .Serum total alkaline phosphatase activity (ALP) was measured by colorimetric determination (20) using a kit from "bioMerieux".The study was conducted during the period from 17 th February 2008 up to 22 nd of December 2008.Standard statistical methods were used to determine the mean, standard deviation (SD), standard error (SE), range (minimum-maximum), and median.Student t-test was used for the comparison between control group and case group.Chi-squared test was used for assessment of hyperparathyroidism and the increase in ALP activity in controls and cases.

Results
Table 1 shows case and control groups that were divided according to their age and sex.

Discussion
Falls are a major health care concern in the frail elderly (21) .The greatest increase in the incidence of fractures in elderly was due mainly to the installation of the osteomalacia and malnutrition as well as to the largest incidence of fall in elderly (22) .The biochemical changes in osteomalacia show increased levels of ALP with normal or decreased serum calcium and phosphate, increased PTH (secondary hyperparathyroidism) and low vitamin D (18)   .The results in the current study have been obtained by investigating 200 elderly whose age's ≥ 60 years.The results in this study showed a highly significant increase (P<0.001) in PTH level in elderly in cases group.This was in agreement with the results obtained by Compston et al., (23) who showed that PTH level was significantly higher in patients with hip fracture and it contributes to bone loss and the high incidence of hip fractures in the elderly population.The results in this study disagree with the result reported by Falch et al. (24) who found that patients with hip fracture had no difference in serum levels of PTH from that of the control.The present study showed a highly significant decrease (P<0.001), in serum calcium and

Control Cases
corrected serum calcium concentration in case group, This was in agreement with Benhamou et al., (25) study who found that hypocalcaemia is common in elderly with fracture proximal femur.Moreover, the results obtained by Sitta et al., (26) showed decreased serum calcium in elderly with fracture which may be due to vitamin D deficiency, which is a major risk factor for bone loss and fracture (27) .The present study were not correspond with the results reported by Pun et al., (28) who found that there is no statistically significant difference in serum calcium concentration between femoral neck fracture patients and the control.The results in our study showed a highly significant decrease (P<0.001), in serum phosphate concentration in case group , This was in agreement with Riaz et al., (29) .On the contrary, the result in our study was in contrast with the result obtained by Pun et al., (28) who showed that there was no significant difference in serum phosphate concentration between femoral neck fracture patients and the control.The results in this study showed a highly significant increase (P<0.001), in ALP activity in cases group , This was in agreement with Sitta et al., (26) who found that serum ALP activity was elevated in elderly with fracture.This result was disagreed with Pun et al., (28) study who found that there was no significant difference in serum ALP activity between femoral neck fracture patients and the control.
In this study, the abnormalities in serum PTH, corrected calcium, phosphate and ALP activity, was done to determine the percentage of osteomalacia in case and control groups.There was a significant higher percentage of combined abnormal biochemical tests (osteomalacia) in cases group (79%), and a higher percentage in males (75%) and females (81.3%) of the same group, and the percentage was higher in females of cases and controls groups.This was in agreement with Sitta et al., (26) who reported that osteomalacia may predispose to fracture in elderly.In contrast, Riaz et al., (29) showed that frequency of osteomalacia in cases of hip fractures was found with no association with known risk factors, and about one fourth of the patients showed abnormal values of serum calcium, phosphorus and ALP.

Conclusion
Osteomalacia was common among patients with fracture neck of femur.