Table 1.

Clinical characteristics of all women with hyperparathyroidism recruited by screening and of sample of women who had not retired from work 5 years before date of screening. Figures are means (SD)

Variable	All patients (n=109)	Current sample
		Cases (n=48)	Controls (n=48)
Age (years)	66.6 (5.8)	62.9 (4.1)*	62.7 (4.2)
Serum calcium (mmol/l)†	2.59 (0.14)	2.59 (0.16)‡	2.34 (0.08)
Serum parathyroid hormone (ng/l)§	66.5 (36.3)	68.9 (41.5)‡	29.3 (8.9)
Serum creatinine (μmol/l)¶	84 (16.9)	82 (14.5)	82 (10.5)
Parathyroid weight (mg)**	591 (892)‡‡	631 (899)††	Not done

^*P<0.0002 v all other patients (Wilcoxon rank sum test).  

^†Ortocrescolophthalein dye binding, corrected for serum albumin, normal range 2.20-2.60 mmol/l.  

^‡P<0.0001 v controls (Wilcoxon signed rank test).  

^§Allegro IRMA (Nichols Institute, San Juan Capistrano, California), normal range 12-55 ng/l, intra-assay and interassay variation at 27 ng/l of 3.4% and 6.1%, respectively.  

^¶Reference range 64-106 μmol/l.  

^**Total weight of abnormal parathyroid tissue at operation.  

^‡‡N=61.  

^††N=33.