It was a descriptive cross-sectional study conducted at Sir Takhtasinhji Hospital, Bhavnagar during August 2012 to August 2013. The study was started after taking permission from Institutional Review Board, Human Ethics Committee (HEC), Government Medical College, Bhavnagar. (Reference letter no. IRB (HEC) no. 302/2012, Medicine Department no. 23/2012).

Inclusion and Exclusion criteria: The study included 50 patients with CRF, aged 12 years and above, admitted in the study hospital during the study period. The CRF was defined as patient having creatinine clearance of <30 mL/min/1.73 m² for greater than six week (stage four and more) [2]. Patients with known case of parathyroid gland disease or malignancy, bone disease or bone malignancy, subjects below 12 years were excluded from the study.

Before data collection, the patients were explained about the study procedure and their informed written consent was taken. A detailed medical history including symptoms like bone pain, fatigue, breathlessness, pedal oedema, decreased urine output was obtained. History of Diabetes Mellitus, Hypertension, Connective tissue disease, Tuberculosis, Nephrotic Syndrome was obtained.

Careful general examination and systemic examination was carried out by the attending physician. All study participants were subjected to investigations like Renal Function Test, serum PTH, serum phosphorus, serum calcium level.

Secondary hyperparathyroidism was diagnosed when serum PTH level was more than 72 pg/mL and serum calcium level below 1.12 Mmol/L. Chemiluminescent (CLIA) techniques was used with instrument Beckman Coulter DxI600.

The data was entered and analysed using Microsoft Office Excel 2010, using data analysis tools and real statistics. Percentage was used to describe the profile of study participants. Pearson correlation coefficient was calculated to show the relationship between serum PTH, serum calcium and serum phosphorus. Statistical significance was defined as p<0.05. All the data collection records were stored confidentially and data entry sheet and analysis file were password protected.

In this study, 50 patients of CKD were enrolled. Among these 43 patients were found with higher level of serum parathyroid level. Thus, the prevalence of secondary hyperparathyroidism was 86%.

Majority of the patients were between 41 to 50 years age group. Mean age was 42.57 years (SD 15.19). Males constituted 48% of the population. Majority of them had breathlessness (40%) as the presenting complaint. Pedal oedema and reduced urine output were noted in 30% and 26% respectively. Hypertension was the most common aetiological morbidity (62%) [Table/Fig-1].

Among the study participants (N=50), 43 had developed secondary hyperparathyroidism. S. calcium level was low in 70% of the patients suggesting hypocalcaemia, while S. phosphorus level was raised in 50% of them [Table/Fig-2].

Majority of the patients with secondary hyperparathyroidism were in the age group of 41 to 50 years (27.91%). Mean age of hyperparathyroidism patients were 44.23 years [Table/Fig-3].

The relationship between S.PTH and S.Calcium was graphically in [Table/Fig-4]. There was linear relationship between these two variables with Pearson correlation coefficient (r) value of -0.3246 (-0.5531 to -0.05083) and p-value 0.02. This suggests moderate level negative correlation: increased level of S.PTH is associated with decrease in S. calcium level. Similarly, [Table/Fig-5] shows graphical presentation of S.PTH and S.Phosphorus relationship. S.Phosphorus positively correlated to S.PTH in the study participants with Pearson correlation coefficient value r=0.15 (0.1279 to 0.4164) and p-value of 0.279.

[Table/Fig-4]:

Relationship between S.PTH and S. Calcium level (N=50).

[Table/Fig-5]:

Relationship between S.PTH and S.Phosphorus level (N=50).

A hospital based cross-sectional descriptive study was carried out to find out the prevalence of secondary hyperparathyroidism in CRF patients. Among the 50 patients of CKD, 43 were found with higher level of serum parathyroid level, thus the prevalence of secondary hyperparathyroidism was 86% in this study.

This was similar to study by Dayma CL et al., in Rajasthan which found 72% prevalence [8]. Patients who were on haemodialysis mostly had stage 5 CKD [9]. According to 2010 registry data from the Korean Society of Nephrology, haemodialysis was the most frequently used renal replacement therapy among the total patients with ESRD [10]. So, declining kidney function may be associated with higher level of PTH.

Disordered mineral metabolism is implicated in pathogenesis of musculoskeletal and vascular complications that afflict patients with advanced CKD. Several studies showed a compelling association between abnormalities in serum phosphate, calcium, calcium x phosphate (Ca x P) product, and PTH levels and all-cause mortality and cardiovascular events [11-13]. There was linear negative relationship between S.PTH and S.Calcium, while S.Phosphorus was found positively correlated to S.PTH in the study participants in this study. This positive correlation may be linked to increased mortality[14] emphasising the importance of SHPT control [15].

Serum calcium level was low in 70% of the patients, while S.Phosphorus level was raised in 50% of them in present study. In study by Mousavi Movahed SM et al., it was found that 28.9% of patients had low serum calcium and serum phosphorus was elevated in 31.1% of haemodialysis patients [16].

Hypertension was the most common aetiological morbidity (62%) among the study participants followed by diabetes (20%) and nephritic syndrome (20%) in present study. Hypertension was most common cause of nephropathy in the study by Dayma CL et al., (62%) followed by nephrotic syndrome (22%), diabetic nephropathy (16%), hepatitis C (12%), connective tissue disease (8%) and tuberculosis (2%) [8], while Owda A et al., found that hypertension was the cause of End Stage Renal Failure (ESRF) in 50% of the patients and diabetes in 37% of the patients [17]. Jorde R et al., had provided the evidence for an association between serum PTH levels and hypertension. In that study, involving 1784 patients over a 7-year period, the authors observed that the serum PTH level was a positive predictor of a change in systolic blood pressure over the study period in men; however it was not significant in women [18]. Serum PTH has also been shown to increase renin secretion and it may have direct effects on arteries and myocytes to promote arterial stiffness and left ventricular hypertrophy, respectively thereby responsible for development of hypertension [19,20].

Secondary hyperparathyroidism was regarded as an important issue among End Stage Renal Disease (ESRD) patients in the study by Mousavi Movahed SM et al., [16]. A 35.55% patients had iPTH levels in the accepted range, while in 37.78% it was above accepted range among fourty five haemodialysis patients in that study and its early detection and treatment may lead to slow the progression of mineral and bone metabolism disorders among CKD patients [16]. One of the conclusions from a meta-analysis study by Segall L et al., was: hyperphosphatemia, secondary hyperparathyroidism, and vitamin D deficiency had been associated with LV hypertrophy and dysfunction. Thus, attaining adequate phosphate, calcium, vitamin D, and serum PTH levels is a rational treatment goal in CKD patients, with or without heart disease, although their benefits for preventing or improving heart failure in these patients have not been proven so far [21].

This study was a single center hospital based study conducted on a limited proportion of patients and is descriptive cross-sectional. A multicentric study with large sample size is recommended that will increase the power as well as external validity of the study.

The results of all of the above studies show that parathyroid abnormalities and disorders of mineral metabolism are common among patients with CKD. The hospital prevalence of secondary hyperparathyroidism in present study was 86%. There was also negative correlation between S.PTH and S.Ca level suggesting lower S.Ca level with higher S.PTH level. There was positive correlation between S.PTH and S.PO4 level that suggest higher value of S.PO4 is associated with higher level of S.PTH. There should be high suspicion of secondary hyperparathyroidism in patients with CKD. Early diagnosis and prompt management of the mineral metabolism disturbances may prevent suffering of the patients from further extra-renal complications.