Mineral bone disorders in hemodialysis patients in the West of Libya :Khairi Ayad, Badreddin Shaibani, Zaynab Rahouma, Yousef AL-Adawi, Fatma Malool, Amina Smaida, Samiha Shamli, Reema Gattusa, Libyan Journal of Medical Sciences

ORIGINAL ARTICLE
Year : 2022 | Volume : 6 | Issue : 1 | Page : 19--22

Mineral bone disorders in hemodialysis patients in the West of Libya

Khairi Ayad¹, Badreddin Shaibani², Zaynab Rahouma¹, Yousef AL-Adawi², Fatma Malool³, Amina Smaida⁴, Samiha Shamli⁵, Reema Gattusa⁶,
¹ Department of Nephrology, Sabratha Teaching Hospital, Sabratha, Libya
² Department of Hemodialysis, AZ Zawiyah Kidney Hospital, Az-zawiyah, Libya
³ Department of Dialysis, Surman General Hospital, Surman, Libya
⁴ Department of Hemodialysis, Agelat Hospital, Al Agelat, Libya
⁵ Department of Hemodialysis, Algmail Hospital, Al Gmail, Libya
⁶ Department of Hemodialysis, Hemodialysis Unit, Zawara Hospital, Zawara, Libya

Correspondence Address:
Dr. Khairi Ayad
Department of Nephrology, Sabratha Teaching Hospital, Sabratha
Libya

Abstract

Background and Objectives: Chronic kidney disease (CKD) is affecting 5%–10% of the world population. As kidney function declines, there is progressive deterioration in minerals homeostasis manifesting as disruption of serum and tissue concentrations of phosphorus, calcium (Ca), and parathyroid hormone (PTH). CKD-mineral bone disorder (CKD-MBD) is a systemic disorder of mineral and bone metabolism manifested by any or a combination of the following: abnormalities of Ca, phosphorus, PTH, Vitamin D metabolism, abnormalities of bone turnover, and vascular or soft-tissue calcification, associated with fractures, cardiovascular disease, and mortality in CKD patients. The study aims to identify the prevalence and pattern of CKD-MBD among hemodialysis patients in the west of Libya. Patients and Methods: A cross-sectional study was carried out on 186 regular hemodialysis patients from five hemodialysis centers in the west of Tripoli-Libya District. All patients were investigated for complete blood count, blood sugar, serum albumin, blood urea, serum creatinine, total Ca level, serum phosphate, serum alkaline phosphatase, and serum intact PTH (iPTH) level. Results: According to the Kidney Disease Outcomes Quality (KDOQ) iPTH level guideline, 88.10% of the studied patients had metabolic bone disorders, and 39.80% showed low bone turnover. About 48.40% were high bone turnover; only 11.80% of studied patients were within the target range according to the KDOQ Initiative guidelines. About 40.36% of studied patients had low calcium levels (below 8.5 mg%), and 35.48% had high phosphorus levels (more than 5.5 mg%). About 61.10% of high bone turnover patients complain of bone pain and 50.50% complain of muscle weakness. Among low bone turnover patients, 36.48% had no symptoms, and 28.38% were complaining of both muscle weakness and bone pain. Conclusions: The prevalence of MBDs among studied patients with abnormal PTH levels is 87.6%, distributed as 39.2% in abnormal low PTH (low bone turnover), and 48.4% in abnormal high PTH (high bone turnover).

How to cite this article:
Ayad K, Shaibani B, Rahouma Z, AL-Adawi Y, Malool F, Smaida A, Shamli S, Gattusa R. Mineral bone disorders in hemodialysis patients in the West of Libya.Libyan J Med Sci 2022;6:19-22

How to cite this URL:
Ayad K, Shaibani B, Rahouma Z, AL-Adawi Y, Malool F, Smaida A, Shamli S, Gattusa R. Mineral bone disorders in hemodialysis patients in the West of Libya. Libyan J Med Sci [serial online] 2022 [cited 2023 Mar 30 ];6:19-22
Available from: https://www.ljmsonline.com/text.asp?2022/6/1/19/353691

Full Text

Introduction

Chronic kidney disease (CKD) is a global public health problem, affecting 5%–10% of the world population,[1] as kidney function declines, there is progressive deterioration in mineral homeostasis manifesting as disruption of serum and tissue concentrations of phosphorus and calcium (Ca), as well as changes in circulating levels of hormones such as parathyroid hormone (PTH). These mineral and endocrine functions are critically important in the regulation of both initial bone formation during growth (bone modeling) and bone structure and function during adulthood (none remodeling).[2] CKD-mineral bone disorder (MBD) describes a broad clinical syndrome that develops as a systemic disorder of mineral and bone metabolism due to CKD, that can manifest with any or a combination of abnormalities of Ca, phosphorus, PTH, Vitamin D metabolism, abnormalities of bone turnover, mineralization, volume, linear growth, and strength, in addition to vascular or soft-tissue calcification. Numerous cohort studies have shown associations between disorders of mineral metabolism and fractures, cardiovascular disease, and mortality in patients with CKD.[3],[4],[5],[6],[7],[8],[9] The prevalence of MBD in hemodialysis patients is high. In Libya, Only one old study[10] showed the prevalence of renal osteodystrophy at 55.3% which was based on old criteria in the classification of CKD-MBD. This work aimed to study the prevalence and pattern of CKD-MBD among hemodialysis patients according to laboratory criteria based on the Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines.

Patients and Methods

A cross-sectional study was carried out on 186 regular hemodialysis patients from five hemodialysis centers in the west of Tripoli-Libya District. After informed consent from all included patients, the study started in April 2019 and ended in January 2020. Exclusion criteria included postmenopausal female patients and other patients who had a condition that can affect laboratory data and symptoms and signs of bone mineral densities (BMDs) such as chronic liver disease, acute infection, malignancy, etc., Before starting hemodialysis, blood samples were collected immediately from an arterial fistula needle (16 gauges) after insertion without tourniquet for complete blood count, blood sugar level, serum albumin, blood urea, serum creatinine, total serum calcium, serum phosphate, serum alkaline phosphatase (ALP), and serum intact PTH (iPTH) levels. Full medical history was revised as well as performing clinical examination for all patients (Serum iPTH assay was performed using electrochemical immunoassay on the fully automated VIDAS® machine). Patients were classified according to the KDOQI guidelines into three groups; low bone turnover group, high bone turnover group, and normal bone turnover group, in addition to the presence of symptoms (bone pain, muscle weakness, or presence of both).

Results

One hundred and sixty-four patients (88.10%) had metabolic bone disorders, of which (39.80%) had low bone turnover, (48.40%) hyperparathyroid (high bone turnover), and only (11.80%) patients were within the range according to the KDOQI guidelines [Table 1]. Hypocalcemia and hyperphosphatemia were seen in (40.86% and 35.48% of patients, respectively) and were markedly noted in the high bone turnover group [Table 2]. Hypercalcemia and hyperphosphatemia were seen in a low turnover group (29.73% and 20.30%) [Table 2]. There was a correlation between iPTH and ALP in both high and low turnover groups (45.95%) of patients with the low turnover group had bone pain, (47.30%) had muscle weakness and only (28.38%) had both symptoms. About 61.10% of patients classified as high turnover bone disorder complaining of bone pain, 50.50% with muscle weakness, 45.5% had both symptoms, and 33.33% had no symptoms at all [Table 3].{Table 1}{Table 2}{Table 3}

Discussions

CKD-MBD is a nearly universal complication of progressive loss of kidney function. Biochemical abnormalities, vascular calcification, and bone fragility constitute the CKD-MBD syndrome. Each is consistently associated with increased risks for morbidity and mortality in large observational studies across the spectrum of CKD.[11],[12],[13] Based on observational and preclinical data and expert opinion, KDOQI an initiative of the National Kidney Foundation, issued its clinical practice guideline for bone metabolism and disease in CKD in 2003,[14] followed by the Kidney Disease: Improving Global Outcomes (KDIGO) CKD-MBD guideline published in 2009, After a KDIGO Controversies Conference held in 2005, the guidelines led to substantial changes in clinical practice, including more frequent laboratory testing of PTH, serum calcium, phosphate, and Vitamin D levels. With the emergence of additional evidence which was reviewed at the 2013 KDIGO Controversies Conference, the KDIGO issued a clinical practice guideline update for the diagnosis, evaluation, prevention, and treatment of CKD-MBD in 2017.[15] Metabolic bone disease is a common complication of CKD and a part of a broad spectrum of disorders of mineral metabolism that occur in this clinical setting and result in skeletal and extraskeletal consequences. Although the histologic examination of undecalcified sections of bone remains the gold standard for the precise diagnosis of renal bone disease, bone biopsy is not widely used in clinical practice due to the invasive nature of the technique. Accordingly, biochemical assessment of disorders of bone and mineral metabolism is the mainstay of the diagnosis and treatment. In addition to the measurements of calcium and phosphorus concentrations, which contribute to hyperparathyroidism, it is essential to obtain a direct index of parathyroid activity by measurements of PTH. Measurements of calcium and phosphorus need to be obtained frequently, and therapy needs to be adjusted according to widely accepted clinical practice guidelines to maintain the calcium and phosphorus concentrations within defined ranges. Accurate assessment of PTH assays remains problematic, even though the assays for PTH have undergone substantial evolution in the past few decades. The early confusion over the interpretation of PTH assays after their initial introduction gave way to a more stable period with the introduction of two-site immunometric assays, which are believed to measure iPTH. This issue complicates practice guidelines such that it seems inappropriate to require rigid adherence to the recommended PTH targets, because the various assays in use may give quantitatively different results. Bone biopsy is the gold standard for diagnosis of renal bone disease,[16] as an invasive procedure and its cost; a bone biopsy is a difficult procedure to do in clinical practice on hemodialysis patients to diagnose BMDs. In clinical practice, serum PTH level is often used together with bone ALP level to assess bone turnover disease, (8.60 ± 1.00), as a noninvasive alternative to bone biopsy.[17]

PTH levels are also predictors of cardiovascular risk in the general population. A cross-sectional study of a large community-based cohort of 3570 subjects with normal renal function and serum calcium levels found that those whose PTH levels were higher than the normal range of normal (i.e., iPTH >62 pg/ml) were significantly more likely to have coronary heart disease than those whose levels were within normal limits (relative risk in men: 1.67, 95% confidence interval [CI]: 1.26–2.23; relative risk in women: 1.78, 95% CI: 1.22–2.57). Furthermore, the subjects whose PTH levels were in the highest quartile (>32 pg/ml in men and 30 pg/ml in women) were at higher risk of coronary disease than those in the lowest quartile (<17 pg/ml in men and 16 pg/ml in women).[18] The K/DOQI guidelines suggested that iPTH should be in target ranges between 150 and 300 pg/ml for patients with stage 5 CKD.[19]

According to iPTH level, 88.10% of studied patients had abnormal BMDs, 48.40% (90 patients) are hyperparathyroid bone disease (iPTH >300 pg/ml), 39.80% (74 patients) low turnover bone disease (iPTH <150 pg/ml), and only 11.80% (22 patients) are within normal range of target level (iPTH Level 150–300 pg/ml) [Table 1]. In an old study, the prevalence of MBDs in Libya was 55.3%. About 28.1% of the patients had laboratory evidence of hyperparathyroid bone disease and 27% of the patients had low turnover bone disease.[11] In a similar study in Egypt, the prevalence of MBD among the studied hemodialysis patients was 85% based on abnormal PTH levels (55% of the patients with high PTH levels and 30% with low PTH levels).[20] Low calcium level (<8.5 mg %) was present in 75 patients (40.2%). The mean calcium level in low turnover bone disease was (9.08 ± 1.14), higher than the hyperparathyroid bone group.

Conclusions

The prevalence of MBDs among studied patients according to abnormal PTH levels was 88.10%. Abnormal low PTH was 39.80% (low bone turnover) and 48.40% abnormal high PTH (high bone turnover). Hypocalcemia and hyperphosphatemia (47.80% and 51.10%, respectively) were markedly high in a high bone turnover group. About 40.86% of the studied patients had low calcium levels (below 8.5 mg%), and 35.48% had high phosphorus levels (more than 5.5 mg%). About 61.10% of high bone turnover patients complaining of bone pain, and 50.50% complaining of muscle weakness. Among low bone turnover patients, 36.48% had no symptoms, and 28.38% complaining of muscle weakness and bone pain. Further studies are advised to establish the size of the problem of mineral bone diseases in Libya.

Acknowledgments

Greatest gratitude to all staff of all included dialysis centers in the study for their cooperation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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