Changes in plasma and red cell volumes during exposure to high altitude.

Training at moderate altitude has been used by athletes to improve the performance at sea level. Not all athletes benefit from altitude training, and there also has been some doubt as to whether red cell volume increases in all subjects. Ten members of the Norwegian Everest Expedition 1985 took part in the present study. Plasma volume was determined by isotope dilution, using 125I-albumin. By simultaneous measurement of hematocrit the total blood volume and red cell volume were calculated. Measurements were done in Oslo (sea level) before departure, and in Base Camp (5300 m) four weeks later. The mean altitude during these four weeks was 4100 m. Red cell volume increased in all participants, and excessively in two of them. Since plasma volume decreased in four subjects, the change in total blood volume was less consistent. In one climber dehydration led to a decrease in total blood volume. While a significant correlation was found between maximal oxygen uptake and red cell volume at sea level, the hematologic response to altitude seemed independent on physical fitness. In one climber the erythropoietic response was so excessive (more than 50% increase in red cell volume), that he had to be hemodiluted.

Evaluation of an enzymatic immunoassay for free thyroxine determination in canine serum.

Free thyroxine (FT4) and cholesterol were measured in 400 dogs with either suspected hypothyroidism or dermatological signs such that hypothyroidism needed to be ruled out. Hypothyroidism was diagnosed in 68 dogs from the history, physical examination and stated lower reference limit (< 7 pmol/L) for FT4 in euthryoid dogs. Dogs with FT4 concentrations in the range 6-9 pmol/L were finally categorized as hypo- or euthyroid either on the basis of retesting after 2 months or on their clinical response to thyroid replacement therapy over at least 2 months. The enzyme immunoassay evaluated in this paper is considered to be of clinical value and offers many advantages compared with radioimmunoassays.

Effect of stress-induced reversible ischemia on serum concentrations of ischemia-modified albumin, natriuretic peptides and placental growth factor.

OBJECTIVE: There is controversy whether new biomarkers are able to identify myocardial ischemia in the absence of myonecrosis. METHOD: We measured NT-pro BNP, NT-pro ANP, ischemia-modified albumin (IMA) and placental growth factor (PlGF) in patients undergoing nuclear stress testing for suspected ischemic heart disease. A thallium scan was used for detection of reversible myocardial ischemia and cardiac troponin T (cTnT) for exclusion of stress-induced myonecrosis. Of 195 patients, 24 with reversible and 62 with no perfusion defect were included in the analysis. Plasma levels were measured before, 18 min and 4 h after stress testing. RESULTS: Of the 86 patients, 52 received an exercise stress and 34 dipyridamol. New myonecrosis indicated by cTnT could be excluded in all patients. Plasma levels of NT-pro BNP and NT-pro ANP before testing were significantly higher in patients who later developed reversible perfusion defects (NT-pro BNP 139.00 (58.25/367.01) pg/mL vs 327.45 (120.50/972.85) pg/mL, p<0.05; NT-pro ANP 732.5 (470.0/1220.0) pg/mL vs 1470.0 (694.0/1910.0) pg/mL, p<0.05). Plasma levels of NT-pro BNP, NT-pro ANP and PIGF did not change significantly after stress testing, IMA levels rose significantly after 4 h in patients with and without reversible perfusion defects. CONCLUSION: The elevation of NTpro BNP and NT-pro ANP at baseline may represent the cumulative effect of repeated bouts of myocardial ischemia. A single brief episode of provoked ischemia does not cause a significant increase of the measured biomarkers beside from IMA after exercise stress test potentially indicating skeletal muscle ischemia.

Inflammation and coronary angiography in asymptomatic type 2 diabetic subjects.

OBJECTIVE: Coronary artery disease (CAD) is prevalent in patients with type 2 diabetes mellitus (T2DM) and because it is often asymptomatic and extensive in comparison with CAD in subjects without diabetes, it represents a diagnostic challenge. The objective of the study was to investigate the prevalence of CAD in asymptomatic T2DM patients utilizing angiography and to investigate its association with cardiovascular (CV) risk factors, the metabolic syndrome and markers of inflammation. MATERIAL AND METHODS: Eighty-two patients with T2DM without symptoms of CAD, and with >or=1 CV risk factor (hypertension, dyslipidaemia, premature familial CAD, smoking or microalbuminuria) underwent a diagnostic stress test and coronary angiography irrespective of stress test results. Stenosis detected in the main coronary arteries >or=50% of lumen diameter was categorized as one-, two- or three-vessel disease. Inflammatory markers were analysed in fasting samples. RESULTS: Fifteen men and two women had significant CAD (21%) (1-vessel disease, n=10; 2- or 3-vessel disease, n=7). Patients with 2- or 3-vessel disease were significantly older and had a longer duration of diabetes, but the prevalence of other traditional CV risk factors or the metabolic syndrome was similar among those with 1-vessel and those with 2- or 3-vessel disease. Sensitivity for CAD of the stress test was low (0.35). The mean level of the pro-inflammatory marker interleukin-6 was elevated in patients with 2- to 3-vessel CAD as compared to patients with no or 1-vessel CAD (p<0.05). CONCLUSIONS: Significant CAD was found in 21% of asymptomatic patients with T2DM with >or=1 CV risk factor. Inflammatory markers may be helpful in identifying patients that are likely to have significant CAD, but larger studies are warranted.

Treatment-related differences in cardiovascular risk factors in long-term survivors of testicular cancer.

OBJECTIVE: Treatment in testicular cancer survivors (TCSs) may be followed by cardiovascular disorders. We have examined whether today's three treatment modalities are associated with a biochemical cardiovascular risk profile. MATERIALS AND METHODS: In this cross sectional study serum inflammatory markers, atherogenic lipoproteins and gonadal hormones were measured in 589 orchiectomized TCSs who have been treated 5-20 years previously. There were 140 patients treated by surgery alone (SURG), 231 who had had infradiaphragmatic radiotherapy alone (RAD), and 218 who had chemotherapy with or without additional surgery (CHEM). RESULTS: (1) The RAD group had higher levels of high-sensitivity C-reactive protein and soluble CD40 ligand compared to the SURG group. (2) The CHEM group had lower levels of high density lipoprotein cholesterol and an increased apolipoprotein B/apolipoprotein A-1 ratio than the SURG group. The prevalence of metabolic syndrome was higher in the CHEM group than in the SURG group. (3) Hypogonadism was significantly more prevalent in the CHEM than in the SURG group. CONCLUSION: Treatment for TC was related to long-term biochemical cardiovascular risk factors by different pathways: Radiation treatment is followed by elevated serum markers of chronic inflammation and endothelial dysfunction, whereas chemotherapy is followed by the development of atherogenic lipid changes and of the metabolic syndrome. This study provides justification for a prospective study of the impact of these treatment modalities on cardiovascular risk in testicular cancer survivors. In the interim testicular cancer survivors should monitor cardiovascular risk over time.

No monthly variations in serum levels of thyroid hormones in human males.

There have been very few reports on rhythmic variation in thyroid hormone concentrations with a periodicity of 4-6 weeks. In an attempt to evaluate whether such a rhythm is a general phenomenon we studied ten healthy male students with weekly blood samples over 12 weeks for T4, T3 and TSH. No rhythmicity could be demonstrated.

MicroCRP: a highly sensitive CRP method applied in the monitoring of renal allograft recipients.

A new ultrasensitive fluoroimmunometric assay for C-reactive protein (CRP), called MicroCRP assay, has a lower detection limit of 0.05 mg/l, and a CV of 7.6% at concentration 0.25 mg/l. The microCRP levels in healthy adults show a skewed distribution, median 0.90 mg/l and mean 1.4 mg/l, with 2.5th and 97.5th percentiles of 0.17 and 4.7 mg/l, respectively, and no gender-related or age differences. Serial microCRP was applied in the monitoring of 37 renal allograft recipients. The operative trauma gave rise to an initial CRP peak, usually on day 2 after transplantation, with a return to preoperative value 1 week after surgery. There were significant CRP elevations (>25%) in all cases of rejections, indicating 100% sensitivity. The microCRP values started to increase about 3 days (range -1 to 9 days) before the rise in creatinine. The microCRP peak tended to be higher in rejection episodes with a vascular component, compared with episodes of cellular rejection (p=0.05). A rise in microCRP at days 7-12 after transplantation seems to predict the risk of rejections later on, and probably reflects the primary immune response to the graft. Recipients without this primary CRP response (only 6 of 37 patients) subsequently had uncomplicated courses. Tracking of values below the traditional lower limit is essential in order to recognize the different CRP peaks. Serial monitoring of microCRP is well suited for clinical use and provides clinical information previously unattainable with other assay systems.

The thyroid function in young men during prolonged exercise and the effect of energy and sleep deprivation.

Thyroid function has been investigated in 24 young military cadets participating in a 5 d ranger training course with heavy physical exercise, calorie deficiency and deprivation of sleep. The cadets were divided into three groups, each differing in the amount of sleep and food consumption. The serum levels of thyroid hormones (T4, FT4, T3, rT3) and TBG showed a biphasic pattern during the course. Initially there was an increased secretion concomitant with an increased deiodination of T4 to T3 and rT3 mainly due to physical exercise. When the activities lasted for several days without sufficient food supply the thyroid secretion decreased simultaneously with an alteration of the peripheral conversion of T4 to rT3 instead of T3. A significant correlation was found between the changes in total and free thyroxine (r = 0.9) and between the increase in rT3 and decrease in T3 (r = 0.6). TSH decreased during the first day of activities and remained low throughout the course. The TSH response to TRH stimulation was greatly reduced during the course due to physical exercise and calorie deficiency. The present investigation demonstrates that the thyroid function is strongly affected by prolonged physical exercise and a negative energy balance, whereas sleep deprivation does not have any significant influence. The results indicate that the alteration observed is not regulated just by the hypothalamo-pituitary-thyroid-axis alone.

Frequency of hyperprolactinaemia due to large molecular weight prolactin (150-170 kD PRL).

Of 605 hyperprolactinaemic sera (prolactin > 1000 mU l-1 determined with PRL DELFIA, Wallac) in the routine diagnostic (PRL was measured in 10,737 sera) 26% had an increased amount of PRL with molecular weight (MW) = 150-170 kD (150-170 kD PRL or bigbig PRL). In a series of serum samples from 660 healthy subjects, only one female with hyperprolactinaemia due to increased 150-170 kD PRL was found. The 150-170 kD PRL constituted less than 1% of the total PRL found in 11 patients with prolactinoma (macroprolactinoma, PRL 8800-500,000 mU l-1). When determined with five different commercially available immunometric assays, the PRL values in the sera with large amounts of 150-170 kD were increased in all sera in four of five assays, although they varied widely. The clinical implications of hyperprolactinaemia due to increased 150-170 kD PRL are still uncertain.