disturbed calcium metabolism may play an important role in the patho - physiology of essential hypertension .
ionized calcium ( ca ) acts as an intracellular second messenger in excitation - contraction coupling in vascular smooth muscle ( vsm ) cells .
the free intracellular calcium concentration determines the tension in vsm cells , thereby contributing to peripheral vascular resistance ( pvr ) .
zidek et al . also found an increased intracellular calcium activity in normotensive subjects with a familial hypertensive disposition in comparison with normotensives without family history of htn .
three extracellular calcium fractions : ionized , protein - bound , and complexed calcium are in equilibrium with one another in the serum .
ionized calcium ( ca ) is the physiologically active form whereas protein - bound calcium is apparently inactive .
the function of complexed calcium , which is bound to small anions such as bicarbonate , citrate , phosphate , and lactate , is uncertain .
treatment of htn is multi - dimensional comprising of dietary modification , weight reduction , regular exercise , and medication .
the calcium channel blockers ( ccbs ) namely nifedipine , amlodipine , diltiazem , verapamil , etc . , form one of the mainstay treatments in htn because they considerably reduce the morbidity and mortality in htn and coronary artery disease .
ccbs block the voltage - gated calcium channels in vsm cells resulting in vasodilatation and decrease in peripheral resistance .
since ccbs act on sarcolemma and reduce the entry of ca from extracellular fluid ( ecf ) to intracellular fluid ( icf ) , it is assumed that the serum ( extracellular ) calcium levels may be altered in hypertensive individuals who are on ccbs .
this study may give an insight into the role of deranged calcium homeostasis in htn .
a total of 31 individuals including 19 hypertensive patients and 12 normotensive subjects in the age group of 3570 years and belonging to both genders attending the out - patient department of general medicine were enrolled into the study after taking written informed consent and approval from institutional ethics committee .
hypertensive patients were grouped into two : those who were on ccbs ( n = 9 ) and those who were on antihypertensive medication other than ccbs ( n = 10 ) .
systolic blood pressure ( sbp ) more than 140 mmhg and/or diastolic blood pressure ( dbp ) more than 90 mmhg with or without previous diagnosis of hypertension were included in hypertensive group .
subjects with sbp less than 140 mmhg , dbp less than 90 mmhg , and without previous diagnosis of hypertension were considered normotensive .
individuals on supplementation with calcium and vitamins including vitamin d were excluded from the study .
subjects with history of diabetes mellitus , ischemic heart disease , retinopathy , neuropathy , and nephropathy were also excluded . the blood pressure ( bp )
was measured in the right arm of the subject in sitting position using sphygmomanometer ( diamond company , pune , india ) after adequate relaxation .
sbp and dbp were recorded , pulse pressure ( pp ) and mean arterial blood pressure ( mabp ) calculated .
ionized calcium ( ca ) was measured by accucare calcium arsenazo iii kit ( lab - care diagnostics pvt . ltd .
at a neutral ph , ca forms a complex with arsenazo iii , the color intensity of which is directly proportional to the concentration of calcium in the sample .
statistical analysis was performed using spss version 13.0 ( spss inc . , il , usa ) and origin pro version 8.0 ( origin lab , ma , usa ) .
differences between the groups were analyzed using analysis of variance ( anova ) followed by tukey honest significant difference ( hsd ) post hoc test .
the blood pressure ( bp ) was measured in the right arm of the subject in sitting position using sphygmomanometer ( diamond company , pune , india ) after adequate relaxation .
sbp and dbp were recorded , pulse pressure ( pp ) and mean arterial blood pressure ( mabp ) calculated .
ionized calcium ( ca ) was measured by accucare calcium arsenazo iii kit ( lab - care diagnostics pvt . ltd . ,
sarigam , india ) according to manufacturer 's instructions . at a neutral ph , ca forms a complex with arsenazo iii , the color intensity of which is directly proportional to the concentration of calcium in the sample .
, il , usa ) and origin pro version 8.0 ( origin lab , ma , usa ) . levene statistic was performed to test the homogeneity of variances .
differences between the groups were analyzed using analysis of variance ( anova ) followed by tukey honest significant difference ( hsd ) post hoc test .
nevertheless , in patients on ccb treatment , serum ca is more compared with patients on antihypertensive medication other than ccb but these differences are statistically not significant [ figure 1 ] .
spearman 's correlation between htn and serum calcium levels is not significant ( p = 0.18 ) .
demographic and test parameters of the participants differences in serum calcium levels between normotensives and hypertensives serum ca levels in different groups
htn is a multi - factorial disorder in which various physiological mechanisms participate to elevate bp .
many hypotheses were proposed about the possible mechanisms underlying essential htn including derangements in serum electrolytes and water balance .
the present study shows no significant difference in serum calcium in hypertensive group compared with normotensive group which is consistent with the findings of kosch et al .
however the results are contradictory with that of others who reported a significant decrease in serum calcium in patients with essential htn compared with normotensive subjects .
serum calcium levels were significantly decreased in both males and females with essential htn and their first - degree relatives when compared with the normotensive controls .
also reported reduced calcium in males with elevated dbp . in the present study the serum calcium levels did not correlate with the levels of bp . serum calcium was found to be significantly correlated with sbp only among those under the age of 40 years .
abnormal cellular ion transport resulting in altered membrane control over intracellular calcium may be related to essential htn .
changes in magnesium levels may contribute to altered cell membrane calcium binding in essential htn .
the free intracellular calcium concentration determines the tension in vsm cells , and thus peripheral vascular resistance .
increased serum calcium is observed in hyperparathyroidism , vitamin d intoxication , multiple myeloma and some neoplastic diseases of bone .
decreased serum calcium is observed in hypoparathyroidism , vitamin d deficiency , steatorrhea , nephrosis , and nephritis .
alternations in intracellular calcium are thought to be involved in the common pathway mediating the secretion and action of many hormones , including the pressor action of catecholamines and angiotensin ii .
25 dihydroxy vitamin d , levels of plasma renin activity , circulating ionized calcium contribute to the pathophysiology of essential htn .
the effects of abnormal calcium and calcium regulating hormone levels may extend to the bp control centers of the central nervous system ( cns ) , particularly the nucleus tractus solitarius .
hypertensive patients on ccb have serum calcium levels more than those on antihypertensive medications other than ccb , although the difference is statistically not significant .
 background : the alterations in extracellular calcium level may influence intracellular calcium level and possibly play a role in the pathogenesis of essential hypertension.aim:the purpose was to find out the association between serum calcium levels and hypertension ; and to compare the serum calcium levels between normotensive controls , hypertensive subjects on calcium channel blockers , and hypertensive subjects on antihypertensive medication other than calcium channel blockers.materials and methods : thirty one individuals including normotensives ( n = 12 ) and hypertensives ( n = 19 ) were enrolled for the study and their blood pressure recorded . 
 hypertensive group was sub divided into two : hypertensives on calcium channel blockers and hypertensives on antihypertensive medication other than calcium channel blockers . 
 serum calcium levels were measured by accucare calcium arsenazo iii kit . 
 differences between the groups were analyzed using anova.results:no significant difference in serum calcium level was found between normotensive and hypertensive groups ; and no correlation was found between calcium levels and the blood pressure . also the difference in serum calcium levels in hypertensive group on calcium channel blockers and those on antihypertensive other than calcium channel blockers was insignificant.conclusions:serum calcium levels 
 are tightly regulated . 
 subtle changes in serum levels do not affect blood pressure . 
Introduction
Materials and Methods
Blood pressure measurement
Estimation of serum calcium
Statistical analysis
Results
Discussion
Conclusions
Limitations of the study