High prevalence of interstitial lung abnormalities in middle-aged never-smokers

Background

Interstitial lung abnormalities (ILA) are incidental findings on chest computed tomography (CT). These patterns can present at an early stage of fibrotic lung disease. Our aim was to estimate the prevalence of ILA in the Swedish population, in particular in never-smokers, and find out its association with demographics, comorbidities and symptoms.

Methods

Participants were recruited to the Swedish CArdioPulmonary BioImage Study (SCAPIS), a population-based survey including men and women aged 50-64 years performed at six university hospitals in Sweden. CT scan, spirometry and questionnaires were performed. ILA were defined as cysts, ground-glass opacities, reticular abnormality, bronchiectasis and honeycombing.

Findings

Out of 29 521 participants, 14 487 were never-smokers and 14 380 were men. In the whole population, 2870 (9.7%) had ILA of which 134 (0.5%) were fibrotic. In never-smokers, the prevalence was 7.9% of which 0.3% were fibrotic. In the whole population, age, smoking history, chronic bronchitis, cancer, coronary artery calcium score and high-sensitive C-reactive protein were associated with ILA. Both ILA and fibrotic ILA were associated with restrictive spirometric pattern and impaired diffusing capacity of the lung for carbon monoxide. However, individuals with ILA did not report more symptoms compared with individuals without ILA.

Interpretation

ILA are common in a middle-aged Swedish population including never-smokers. ILA may be at risk of being underdiagnosed among never-smokers since they are not a target for screening.

Assessment of Global Lung Function Initiative (GLI) reference equations for diffusing capacity in relation to respiratory burden in the Swedish CArdioPulmonary bioImage Study (SCAPIS)

The Global Lung Function Initiative (GLI) has recently published international reference values for diffusing capacity of the lung for carbon monoxide (D _LCO). Lower limit of normal (LLN), i.e. the 5th percentile, usually defines impaired D _LCO We examined if the GLI LLN for D _LCO differs from the LLN in a Swedish population of healthy, never-smoking individuals and how any such differences affect identification of subjects with respiratory burden.Spirometry, D _LCO, chest high-resolution computed tomography (HRCT) and questionnaires were obtained from the first 15 040 participants, aged 50-64 years, of the Swedish CArdioPulmonary bioImage Study (SCAPIS). Both GLI reference values and the lambda-mu-sigma (LMS) method were used to define the LLN in asymptomatic never-smokers without respiratory disease (n=4903, of which 2329 were women).Both the median and LLN for D _LCO from SCAPIS were above the median and LLN from the GLI (p<0.05). The prevalence of D _LCO <GLI LLN (and also <SCAPIS LLN) was 3.9%, while the prevalence of D _LCO >GLI LLN but <SCAPIS LLN was 5.7%. Subjects with D _LCO >GLI LLN but <SCAPIS LLN (n=860) had more emphysema (14.3% versus 4.5%, p<0.001), chronic airflow limitation (8.5% versus 3.9%, p<0.001) and chronic bronchitis (8.3% versus 4.4%, p<0.01) than subjects (n=13 600) with normal D _LCO (>GLI LLN and >SCAPIS LLN). No differences were found with regard to physician-diagnosed asthma.The GLI LLN for D _LCO is lower than the estimated LLN in healthy, never-smoking, middle-aged Swedish adults. Individuals with D _LCO above the GLI LLN but below the SCAPIS LLN had, to a larger extent, an increased respiratory burden. This suggests clinical implications for choosing an adequate LLN for studied populations.

From COPD epidemiology to studies of pathophysiological disease mechanisms: challenges with regard to study design and recruitment process: Respiratory and Cardiovascular Effects in COPD (KOLIN)

Background: Chronic obstructive pulmonary disease (COPD) is a largely underdiagnosed disease including several phenotypes. In this report, the design of a study intending to evaluate the pathophysiological mechanism in COPD in relation to the specific phenotypes non-rapid and rapid decline in lung function is described together with the recruitment process of the study population derived from a population based study. Method: The OLIN COPD study includes a population-based COPD cohort and referents without COPD identified in 2002-04 (n = 1986), and thereafter followed annually since 2005. Lung function decline was estimated from baseline in 2002-2004 to 2010 (first recruitment phase) or to 2012/2013 (second recruitment phase). Individuals who met the predefined criteria for the following four groups were identified; group A) COPD grade 2-3 with rapid decline in FEV₁ and group B) COPD grade 2-3 without rapid decline in FEV₁ (≥60 and ≤30 ml/year, respectively), group C) ever-smokers, and group D) non-smokers with normal lung function. Groups A-C included ever-smokers with >10 pack years. The intention was to recruit 15 subjects in each of the groups A-D. Results: From the database groups A-D were identified; group A n = 37, group B n = 29, group C n = 41, and group D n = 55. Fifteen subjects were recruited from groups C and D, while this goal was not reached in the groups A (n = 12) and B (n = 10). The most common reasons for excluding individuals identified as A or B were comorbidities contraindicating bronchoscopy, or inflammatory diseases/immune suppressive medication expected to affect the outcome. Conclusion: The study is expected to generate important results regarding pathophysiological mechanisms associated with rate of decline in lung function among subjects with COPD and the in-detail described recruitment process, including reasons for non-participation, is a strength when interpreting the results in forthcoming studies.

Self-rated health as a predictor of outcomes of type 2 diabetes patient education programmes in Denmark

OBJECTIVE

To explore if self-rated health (SRH) can predict differences in outcomes of patient education programmes among patients with type 2 diabetes over time.

STUDY DESIGN

This is an observational cohort study conducted among 83 patients with type 2 diabetes participating in patient education programmes in the Capital Region of Denmark.

METHODS

Questionnaire data were collected by telephone interview at baseline and 2 weeks (77 participants, 93%) and 12 months (66, 80%) after the patient education ended. The seven-scale Health Education Impact Questionnaire (HeiQ) was the primary outcome. The independent variable was SRH, which was dichotomized into optimal or poor SRH. Changes over time were assessed using mean values and standard deviation (SD) at each time point and Cohen effect sizes. Odds ratios and 95% confidence intervals were calculated for the likelihood of having poor SRH for each baseline sociodemographic and health-related variable.

RESULTS

Twelve months after patient education programmes, 60 (72%) patients with optimal SRH at baseline demonstrated increased self-management skills, overall acceptance of chronic illness, positive social interaction with others, and improved emotional well-being. Participants with poor SRH (23, 28%) reported no improvements over time. Not being married (odds ratio [OR] 7.79, P < 0.001), living alone (OR 4.93, P = 0.003), having hypertension (OR 8.00, P = 0.031), and being severely obese (OR 4.07, P = 0.009) were significantly associated with having poor SRH. After adjusting for sex, age and vocational training, marital status (OR 9.35, P < 0.001), cohabitation status (OR = 4.96, P = 0.005) and hypertension (OR 10.9, P = 0.03) remained associated with poor SRH.

CONCLUSIONS

We found a strong association between SRH and outcomes of patient education, as measured by the HeiQ, at 12 months. Only participants with optimal SRH appeared to benefit from patient education. Other patient characteristics may be responsible to explain the observed difference between patients with optimal and poor SRH.

[Incidence of adverse events in hospitals. A retrospective study of medical records]

INTRODUCTION

Over the past decade a number of studies on the incidence and preventability of adverse events in the health care have been published in the US, Australia and the UK. So far no similar study has been performed in Denmark. In order to determine whether foreign findings could be generalised to Danish health care, a pilot study on adverse events was carried out in Danish acute care hospitals.

METHOD

Chart reviews were carried out on 1.097 acute care hospital admissions, sampled from the central Danish National Patient Register. The sample was truly proportional with no over-sampling of high-risks groups. Chart reviews was done in 17 different acute care hospitals, reviewing between 20 and 204 admissions per hospital. Adverse events was identified using a three-step procedure: 1) Nurse screening by 18 criteria identifying high-risk groups. 2) Independent reviews by pairs of consultants. 3) In case of disagreement between second step consultants, two additional independent reviews was performed by new consultants (internist and surgeon) followed by conference. All chart reviews were performed independent of medical specialty. All nurses and doctors were senior and experienced clinicians.

RESULTS

In 114 admissions 176 Adverse Events (AEs) were identified. The prevalence of admissions with adverse events were 9.0% of all admissions. Preventability of adverse events was found in 46 of admissions (40.4% of AEs). The adverse events caused on average a 7.0 days prolonged hospital stay. Most adverse events resulted in minor, transient disabilities. Permanent disability or death in relation to adverse event were recorded in 30 admissions.

DISCUSSION

The findings from the Danish Adverse Event Study are similar to the results found in Australia, United Kingdom and the United States. It is therefore recommended that further Danish research, is directed towards high-risk groups focussing on narratives and intervention and towards research in primary health care.

Comparison of magnesium and methyldopa for the control of blood pressure in pregnancies complicated with hypertension

OBJECTIVES

Although magnesium is now the drug of choice for the prevention of eclamptic seizures only few studies have evaluated whether magnesium may reduce blood pressure in pregnancies complicated with hypertension.

METHODS

A total of 33 patients with pregnancy-induced hypertension were randomized to either magnesium or methyldopa treatment. Of these 16 received magnesium and 17 methyldopa. The treatment comprised a 48-hour magnesium infusion followed by oral magnesium tablets until 3 days after delivery or 250 mg methyldopa 4 times a day in a similar period.

RESULTS

Patients treated with magnesium had 1 day after inclusion a statistically significantly lower systolic blood pressure compared to the level in the methyldopa group (138.1 +/- 11 vs. 147.6 +/- 11 mm Hg; p < 0.05), but no difference was observed in diastolic blood pressure (92.0 +/- 6.6 vs. 96.0 +/- 10.1 mm Hg; NS). From the 5th day of inclusion and until delivery both systolic and diastolic blood pressure were significantly lower in the magnesium group (p < 0.05). Including all blood pressure measurements in a single analysis showed that both systolic (138 +/- 13 vs. 148 +/- 15 mm Hg; p < 0.0001) and diastolic (92 +/- 10 vs. 94 +/- 10 mm Hg; p < 0.05) blood pressure were lower in the magnesium group compared to the methyldopa group. There was no difference between the two groups regarding gestational age at delivery, birth weight, Apgar scores and pH in umbilical cord blood.

CONCLUSION

This preliminary study demonstrates that magnesium treatment lowers blood pressure in pregnancies complicated with hypertension. The effect is without any adverse effect on maternal and neonatal well-being.

Prevalence of hypercalcaemia in normal and in hospital populations

The purpose of the present study was to review the literature with respect to the prevalence of hypercalcaemia in normal and in hospital populations. Pertinent studies were selected from the MEDLINE database (1980 to March 1995) and through the bibliographies of selected articles. Hypercalcaemia is one of the most common metabolic disorders in malignant diseases and develops in 3-30% of such patients. Hypercalcaemia of malignancy is the most common cause of hypercalcaemia followed by primary hyperparathyroidism in hospital populations. The most common cause in normal populations is primary hyperparathyroidism followed by transient hypercalcaemia. The prevalence of hypercalcaemia shows a large variation in hospital populations ranging from 0.17% to 2.92%. The prevalence in normal populations varies between 1.07% and 3.9% and, surprisingly exceeds the level in hospital populations. The discrepancies between prevalences may be due to varying referral patterns, different distribution of specialities causing different hospital populations and different definitions of hypercalcaemia. Hypercalcaemia presents a diagnostic problem. The percentage of cases of hypercalcaemia that are actually diagnosed has been observed to be as low as 25% in hospitals, in which laboratory results remain unreported unless requested. But even when presented, 20-50% of the cases are overlooked.

Combined reports on serum calcium and discriminant functions increase the diagnostic rate of hypercalcaemia

Hypercalcaemia is a condition easily overlooked by the clinician. Prompted by the observation that computerized reminders could increase the awareness, we have examined whether the combined reporting of increased serum calcium results and the results from diagnostic discriminating calculations could increase the clinical awareness of hypercalcaemia. Albumin-corrected serum calcium was estimated in all 4500 patients admitted to the hospital during a period of 2 months. Eighty-seven patients were found with hypercalcaemia and were assigned randomly to 2 groups: A (40 patients) and B (47 patients). In group A, the increased serum calcium and the results of the discriminant functions were reported; in group B, the serum calcium was reported only if requested and the discrimination diagnosis withheld. The clinical records were examined 3 weeks after admission. At this time the records in group A contained a relevant clinical diagnosis explaining the hypercalcaemia in 81% of the cases. This was in contrast to only 31% of the records in group B. We conclude that this combined reporting leads to a considerable improvement in the clinical awareness of hypercalcaemia and results in a diagnosis explaining the condition in the majority of cases.

Transfer of hypercalcemia discriminant functions between local hospitals

Transferability of discriminant functions is potentially useful both from an economical point of view and because, in general, medical knowledge, in this case discriminant functions, should be transferable. In the present study we have evaluated the transferability of discriminant functions, estimated from routine laboratory analysis, age and sex in two consecutively recorded populations with hypercalcemia including 162 and 257 patients with hypercalcemia. Discriminant functions were developed for each sex to distinguish between hypercalcemia associated with malignancy and hypercalcemia associated with other medical diseases. The total diagnostic accuracy in Herlev was 82 and 78%, in women and men, and increased to 87 and 86% in both sexes considering cases classified with posterior probability levels of 60%. In Hvidovre the total diagnostic accuracy was 81 and 84% in women and men, and increased to 83 and 89% at posterior probability levels higher than 60%. Transfer of the discrimination functions between the hospitals was followed by a decrease in diagnostic accuracy of 6-16%. At a posterior probability of 60% the diagnostic accuracies were 79% or more in the receiving hospital, in both sexes, except for men in Hvidovre. In relation to these results the concept of genuine and non-genuine transfer factors is introduced and discussed.

Within-centre evaluation of hypercalcaemia discriminant functions 5 years after their development

Diagnostic hypercalcaemia discriminant functions, discriminating between clinically significant and non-significant hypercalcaemia, were tested 5 years after their development in order to evaluate the impact of time on their diagnostic capacity. Two populations, consisting of 257 and 129 patients with hypercalcaemia, were consecutively recorded, during six and three months respectively, 5 years apart under similar circumstances. The prevalence of hypercalcaemia was comparable in both populations, being 2.57 and 2.38% respectively (non-significant) (NS). The female/male ratio was 1.9 and 1.7 (NS). The discriminant functions correctly classified 81 and 80% of the women, respectively (NS) and respectively 75% and 64% of the men (NS) in the first and second recorded populations.

Long-term changes in bone mass after partial gastrectomy in a well-defined population and its relation to tobacco and alcohol consumption

We studied the long-term effect of partial gastrectomy on bone metabolism in a well defined population of gastrectomized patients compared to an age- and sex-matched group with unoperated peptic ulcers (controls). We selected 61 individuals between 61 and 70 years old at the time of investigation who had been operated on at the same surgical department an average of 20 years earlier. Compared to unoperated ulcer patients, we found reduced bone mass of the distal forearm in the operated groups. The serum level of calcidiol was significantly reduced in Billroth I (BI) operated women and insignificantly lower in the other operated groups. In men, ionized and total calcium was reduced, and 24-hour excretion of hydroxyproline in the urine as increased (p < 0.05). Biochemical signs of osteomalacia were found in one gastrectomized patient only. There were no significant differences between operated and unoperated patients in serum levels of alkaline phosphatases, iPTH, calcitriol, or the 24-hour urine calcium/creatinine excretion, even though there was a trend toward lower 24-hour urine calcium/creatinine ratio and increased levels in iPTH in the operated groups. There was no correlation between the daily alcohol consumption or cumulative tobacco consumption and bone mineral content in each group. Gastrectomized women smoked much more than control women, and smoking may be a determinant factor for the bone loss, as it is in healthy persons. Operated patients had a lower intake of milk products. All patients were exposed to sunlight for more than 3 hours/week. It is suggested that osteopenia after gastrectomy might be caused by calcium depletion rather than lack of vitamin D. The consumption of tobacco but not of alcohol was connected to bone loss.

Do local hospitals meet the analytical goals for the use of common reference intervals?

Blood samples were obtained from 183 blood donors and measured in two hospitals in the same geographical area using identical reference intervals and measuring equipment. The analytical bias of the clinical chemical analyses was investigated through paired measurements. The results showed that out of 15 routine analyses only four meet the goals for acceptance of common reference intervals, of which at least three were of clinical significance. The problems were reflected in the quality assessment results but, nevertheless, no action seems to have been taken.

Serum ionized calcium, parathyroid hormone and phosphate in uremic patients during and between hemodialysis

The serum concentrations of actual ionized calcium (at actual pH), adjusted ionized calcium (at pH 7.4), pH, intact parathyroid hormone (PTH) and phosphate were studied in ten patients during and between two hemodialysis sessions using a dialysate containing 1.66 mmol/l of calcium. Actual ionized calcium and adjusted ionized calcium increased during hemodialysis from 1.19 to 1.38 and 1.43 mmol/l, respectively (mean values) and returned to predialysis values within five and nine hours postdialysis. Serum PTH decreased from 165 ng/l to 55 ng/l (median values) during hemodialysis but two-hour postdialysis the level did not differ significantly from the predialysis level. Serum phosphate decreased from 2.05 mmol/l to 1.11 mmol/l during hemodialysis, and increased slowly towards the predialysis level. The level of pH increased from 7.40 to 7.47 during hemodialysis and reached predialysis level after nine hours. In a multivariate analysis including actual and adjusted ionized calcium, pH, phosphate and PTH, only actual or adjusted ionized calcium was associated with the level of PTH. We conclude that the effect of dialysate calcium on the levels of ionized calcium and PTH is of very short duration postdialysis.

Filtering clinically significant hypercalcaemia from non-significant hypercalcaemia at the laboratory level

In an earlier study it was shown, that, in a hospital population, only about 30% of patients with hypercalcaemia had the diagnosis identified and so an alarm filter was developed, at the laboratory level, to differentiate between clinically significant and clinically non-significant hypercalcaemia. The filter correctly classified 84% and 77% of women and men with hypercalcaemia, respectively, with respect to the clinical significance of the hypercalcaemia. The sensitivity and the specificity of the discriminant functions were 90% and 73% in women and 80% and 67% in men. The alarm filter was based on a two-step procedure. The patients were primarily classified by the discriminant functions into one of the following medical diagnoses related to hypercalcaemia: primary hyperparathyroidism, malignancy, and transient hypercalcaemia. Based on this classification the patients were characterized as having either a clinically significant or non-significant hypercalcaemia. The alarm filter was based on two discriminant functions. The discriminant variables were phosphate, albumin, protein, LD, and a haemoglobin in women, and albumin, protein, ALP, and age in men. Missing values were estimated. The discriminant variables were selected from 17 possible discriminant variables, all measured by routine, and age. The study group comprised 257 patients with hypercalcaemia, consecutively registered, during half a year. The classification efficiency of the discriminant functions were based on comparison of results obtained by cross-validation of the discriminant functions, and the medical diagnosis decided by the clinicians in the respective departments of the hospital. The medical diagnoses were based on principles and definitions generally used in the departments with no knowledge of the results assessed by the discriminant functions.

[Magnesium therapy in pregnancy-induced hypertension and pre-eclampsia]

At present, magnesium treatment is employed routinely in the treatment of hypertension induced by pregnancy (PIH) and preeclampsia in USA with the object of preventing seizures. In USA the treatment of election consists of intravenous infusion of large doses of magnesium sulphate in order to obtain a therapeutic concentration. The anticonvulsive mode of action of magnesium is only partially understood. Magnesium is presumed to block the neuromuscular transmission but a central effect cannot be excluded. Treatment with magnesium has, in addition, an antihypertensive effect. The effect of magnesium on the blood pressure is probably a direct vasodilatory effect which explains the ability of magnesium to reduce the maternal blood pressure. Probably the same mode of action is responsible for the relaxing effect of magnesium on the vascular tone in the umbilical and placental vessels. This can probably explain the favourable effect of magnesium on the birth weight. Even if magnesium treatment implies a potential risk for neonatal hypermagnesemia and hypocalcaemia, only few side effects have been reported.

Impaired 1,25-dihydroxyvitamin D production in pregnancy-induced hypertension

The aim of the study was to evaluate the calcium metabolism in pregnancy-induced hypertension. Fifty-three women with pregnancy-induced hypertension were studied and the control groups comprised 20 women with uncomplicated pregnancies in the third trimester and 51 non-pregnant women, respectively. The mean serum concentrations of 1,25-dihydroxyvitamin D in women with pregnancy-induced hypertension was low (38.6 +/- 21.4 pg/ml) compared to women with uncomplicated pregnancies (91.0 +/- 18.2 pg/ml), but comparable to levels in non-pregnant women (32.2 +/- 11.9 pg/ml). Mean serum levels of PTH and ionized calcium were comparable in women with pregnancy-induced hypertension and women with uncomplicated pregnancies. In conclusion, the calcium metabolism in pregnancy-induced hypertension was changed compared to uncomplicated pregnancies with respect to the serum concentration of 1,25-dihydroxyvitamin D.

Serum concentrations of intact parathyroid hormone during late human pregnancy: a longitudinal study

In the present study an assay reactive with the intact PTH molecule supposed to be the biological active has been used for measurements in 10 normal pregnant women during the late pregnancy and post-partum. Simultaneously serum concentrations of ionized calcium, phosphate, magnesium and albumin were determined. Serum concentrations of intact PTH were low compared to non-pregnant levels, while concentrations of ionized calcium, phosphate, magnesium (corrected) were unaffected.

[Consumption of milk among pregnant women and its significance for the intake of calcium and fats]

Out of a total of 158 pregnant women, 55 accepted participation in a dietary investigation for seven days with the object of assessing the consumption of milk by pregnant women and the significance of this for the intake of energy-providing dietary constituents and certain minerals. The diet in pregnant women contained more fat (43.2%) and the relationship between polyunsaturated and saturated fatty acids (P/S-relationship) (0.25) was less than that recommended. The daily dietary content of fibre of 20.7 g/day was lower than the recommended intake. Calcium, phosphate and magnesium intakes constituted 180%, 131% and 64% respectively, of the recommended daily intake. The average intake of milk (buttermilk, skim milk, low fat milk and whole milk) was 482 g/day. The calcium content of the milk constituted, on an average, one third of the total calcium intake. The content of fat and saturated fatty acids in the milk constituted 7% and 10%, respectively, of the total intake. Four of the pregnant women had a daily calcium consumption of less than the recommended intake (1,000 mg/day). The same women had the lowest consumption of milk and energy in the group investigated. The results suggest that the dietary consumption is adequate to cover the calcium requirements. Extra calcium supplements should only be recommended for pregnant women with limited consumption of milk and other milk products. Pregnant women should be advised to take increased quantities of magnesium and to reduce the fat intake.

Awareness of hypercalcaemia in a hospital population?

In a hospital population all patients with hypercalcaemia were registered consecutively during a 6-month period. Fifty per cent of the patients having hypercalcaemia, which was defined as serum calcium concentrations (albumin corrected) above normal mean + 3 standard deviations, had a serum calcium analysis requested. Of these between 14% and 96%, dependent on the clinical diagnosis and the degree of hypercalcaemia, had the hypercalcaemia identified. Since the prevalence of hypercalcaemia was estimated to be 2.6% and only about 1:4 was identified by the clinicians, correct diagnosis of hypercalcaemia seems to be a problem.

Magnesium supplement in pregnancy-induced hypertension. A clinicopathological study

The placenta and the umbilical cord obtained from 18 women with pregnancy-induced hypertension were investigated by light microscopy. The umbilical artery was studied by electron microscopy. 10 placentae and umbilical cords from normal pregnancies served as controls. The study was performed as a double-blind randomized controlled study in which 11 women were allocated to magnesium and 7 to placebo treatment. The treatment comprised a 48-hour intravenous magnesium/placebo infusion followed by daily oral magnesium/placebo intake until one day after delivery. Magnesium supplement increased birth weight and placental weight significantly. Light microscopic study of the placentae and the umbilical cord arteries showed no difference between the three groups concerning the occurrence of infarctions, cytotrophoblastic hyperplasia, vasculo-syncytial membranes, basement membrane thickening, stromal fibrosis or intervillous fibrin. Ultrastructurally, the endothelial cells of the umbilical arteries from women with pregnancy-induced hypertension showed a significant increase in the amount of dilated endoplasmic reticulum and basal laminae thickness when all 18 cases were compared with the controls. There was no significant difference when the magnesium group, the placebo group and the control group were compared separately. The present study suggests that magnesium supplement has a beneficial effect on fetal growth in pregnancy-induced hypertension. With regard to the light and electron microscopic changes we were unable to demonstrate any significant difference between the magnesium, placebo and control groups.

Estrogen receptors appear undetectable in the C-cells of the human thyroid gland

An attempt was made to explain the bone-preserving effect of estrogen by analysis of estrogen receptors (OER) in the calcitonin-producing C-cells of the human thyroid gland. Thyroid tissue from twenty patients with benign hyperthyroidism and three patients with medullary thyroid carcinoma was used. The C-cells were identified immunohistochemically using a polyclonal antibody to calcitonin, and by a similar staining technique the adjacent sections were stained for the OER protein using a monoclonal antibody (H 222-ABBOTT, USA). In spite of an intense nuclear staining of the positive control tissue (an OER positive breast carcinoma) no specific OER-staining was identified in C-cells or any other cells of the thyroid gland. Neither a dextran-coated charcoal assay nor a solid-phase immunoenzyme assay revealed any quantitative OER activity in tissue homogenates. Various observations point to a regulating mechanism between calcitonin and estrogen. The nature of this mechanism is not known, but according to our study it is unlikely to be a direct one.