human chorionic gonadotropin ( hcg ) is a heterodimeric hormone secreted by the trophoblastic tissue of the placenta as well as certain tumors . small amounts of hcg have been reported to be secreted by the pituitary gland in non - pregnant females and males . various commercial assays are available in the market to detect hcg in both serum and urine . they are also used in the diagnosis , management and follow - up of ectopic pregnancy , trophoblastic diseases and germ cell tumors . in the absence of pregnancy and neoplasia , elevated hcg in females studies have attributed this to false positivity due to the presence of heterophilic antibodies or a physiologic increase in hcg in post - menopausal females . low positive hcg values have led to empirical chemotherapy in some and delay or cancellation of important medical procedures in others . we report a series of non - pregnant female patients with chronic renal failure with positive serum hcg over a period of 1 year from our center . the database of all patients who underwent renal transplant at our center from july 2007 through july 2008 was reviewed . a total of 171 patients with end - stage renal disease were screened for renal transplantation during that year , 109 males and 62 females . the mean age of female patients was 53.7 years ( range 23 - 79 years ) . for pre - transplant screening , all the female patients underwent serum hcg screening to rule out pregnancy , irrespective of their ages . hcg screening was carried out using  hcg plus kit  from roche pharmaceuticals , usa ( 0 - 5 iu / five out of 62 ( 8% ) female patients had a positive hcg test ( 5 the test was repeated in 4 four out of five patients to rule out any discrepancy . a total of 3 patients underwent successful renal transplantation while one is still on the waiting list . two patients were dialysis - dependent while the remaining was being worked up for pre - emptive transplant . the mean value of hcg in post - menopausal patients was 8.4 ( range 6 - 10 ) . however , hcg was slightly higher in premenopausal patient . epstein - barr virus serologies were positive in all patients ; two were cytomegalovirus positive . no other common environmental exposures , which could have led to the production of heterophilic antibody , could be identified in them . hcg- is identical to the -subunit of luteinizing hormone ( lh ) , follicle stimulating hormone ( fsh ) and thyroid stimulating hormone while  subunit is exclusive to each hormone . normally produced by syncytiotrophoblast cells of placenta , hcg is also secreted by trophoblastic and gastrointestinal tumors . hcg is produced in very small amounts in men and non - pregnant women , primarily from the anterior pituitary gland . in pregnancy , 30% of hcg the remainder is cleared by other pathways , likely by metabolism in the liver and kidneys . the biological function of hcg is maintaining secretion of progesterone from corpus luteum until the placenta takes over this function . various other degraded and dissociated forms of hcg are present in the serum and urine , with little or no biological activity . besides being used as a marker of pregnancy and certain tumors , hcg screening tests are also carried out before most medical interventions in female patients . most immunoassays use different combinations of antibodies against different sites on hcg or its subunits . some assays detect non - nicked hcg alone , some detect non - nicked hcg and free  hcg while others detect both nicked ( biologically inactive ) and non - nicked hcg . though these tests have high sensitivity and specificity , the heterogeneity in the assays may lead to false positive results . heterophilic antibodies in humans may cross - react with animal immunoglobulin used in the assay and can result in falsely positive tests . these antibodies develop following exposure to serum or tissue antigens of animals and occur in about 3 - 15% of healthy individuals . as a consequence , however , it has been observed that the values in such cases of false positive results range from 100 iu / l to 500 iu / l , a good deal higher than our results . moreover , the assay used in our patients contained blocking antibodies , which bind these heterophilic antibodies and prevent cross reactions . studies have shown that the serum concentration of hcg increases in post - menopausal females . suginami and kawaoi obtained serial sections of pituitary glands at autopsy from women of various chronological ages . they concluded that hcg - like substance was localized in the gonadotrophs of the pituitary glands obtained from post - menopausal females . stenman et al . , in their study , showed that treatment of post - menopausal women with a combination of estrogen and progesterone reduced their serum hcg levels by half . this further points towards the pituitary production of hcg in them . in studies on female cohorts , hcg levels have been found to be proportionate to increases in fsh after menopause . other authors consider pituitary hcg to be produced with increasing menopausal production of lh , owing to the decreased negative feedback by progesterone . case reports have implied that hcg concentrations 5.0 iu / l should not be considered abnormal in post - menopausal women . in a study in females more than 55 years of age , hcg levels > 5 iu / l in 16/240 ( 6.7% ) were observed . , in their paper , suggested that the upper limits of normal of serum hcg for post - menopausal women be increased to 14.0 iu / l . thus , this post - menopausal rise in hcg may explain the elevated hcg in four of our patients . the role of chronic kidney disease ( ckd ) as a cause of elevated hcg levels has not been studied . it is well - known that 30% of hcg being produced is cleared by the kidney and an additional fraction metabolized by it . in our cohort of female ckd patients , hcg levels > 5 iu / l were observed in 5/62 ( 8.1% ) . in the subset of patients with age > 55 , hcg levels more than 5 iu / ml were noted in 4/30 ( 13.3% ) . thus , the presence of ckd in our patients may have served to elevate the hcg levels further in them . however , the factors , which elevate the hcg levels in only some patients with ckd remain poorly understood . a prospective cross - sectional study on pregnant patients showed that mild renal or hepatic impairment has no effect on maternal serum screening , which includes hcg . whether more severe renal disease ( such as in our patients ) has an effect on hcg excretion is yet to be ascertained . reduced testosterone concentration with the increase in level of gonadotropins , including lh and fsh , in has been attributed to a wide range of factors including aging , chronic inflammation , malnutrition and vascular disease . in these circumstances , a pituitary overproduction of hcg in parallel to fsh / lh , akin to the reports above , also appears plausible . many women experience delays in their management and postponement of surgical procedures because of elevated hcg . instances of needless chemotherapy administered to such women because of the presumption of cancer have also been reported . our patients also had to undergo various other investigations increasing the overall cost and delaying treatment . these included obstetrics / gynecology referrals with follow - up , pelvic ultrasound examinations ( one or more ) and serial blood testing . the transplant procedure itself was rescheduled in one of the patients on account of the positive hcg . in summary , healthy non - pregnant females can have elevated hcg either due to false positive results or menopausal status . large - scale studies are needed to ascertain the prevalence of a positive hcg test by conventional criteria in post - menopausal females in the general population . correcting hcg levels for age and co - morbidities may be prudent in reducing procedural delays and treatment costs in such women .