On commonness and rarity of thyroid hormone resistance: a discussion based on mechanisms of reduced sensitivity in peripheral tissues.

Reduced sensitivity to thyroid hormone (TH) in peripheral tissues can occur as defects in TH transport into the cell, intracellular TH metabolism, cytosolic mechanisms, TH entry into the nucleus, thyroxin receptors (TRs) and receptor binding, transcription and post-transcriptional mechanisms. Current literature reveals an extensive list of mutations, drugs, toxins, metabolites and autoimmune antibodies that may impair TH action in the cell, but such impairment may not be picked up by assays of TH and TSH in blood plasma. Substances may induce tissue specific resistance to thyroid hormone (RTH), e.g. by affecting numbers of different TR isoforms. Recent literature also indicates mechanisms by which different conditions, for example, chronic fatigue syndrome (CFS), chronic renal failure (CRF) and nonthyroidal illness, can be accompanied by acquired RTH caused by inhibition of TH metabolism, cell uptake, TR binding and transcription. This prompts us to reassess commonness and rarity of congenital vs. acquired RTH. We hypothesise that observed clinical symptoms of hypothyroidism in chemically euthyroid patients are typically caused by changes in hormonal systems, autoimmune antibodies, metabolites or other substances in the body, leading to reduced sensitivity to TH in peripheral tissues. These changes may be a by-product of other processes and a reversible biological response in the body, and may also result in chronic acquired RTH. Antibodies may prove to be the most common cause of chronic reduction in TH sensitivity. It is argued that the acquired form of RTH, caused by endogenous and exogenous sources, may indeed be more common than the congenital, as in insulin resistance. If acquired RTH exists, then it may not be picked up by blood assays of TH and TSH. An appropriate test to assess TH action in peripheral tissues is therefore greatly desired.

Blood sampling in doping control. First experiences from regular testing in athletics.

We report the results from blood sampling taken for the first time during doping control in athletics. The study includes samples from 99 athletes tested during IAAF-meetings in 1993-94. Blood doping with allogenic blood was not detected. The distribution of haemoglobin levels in athletes did not differ markedly from that found in controls. Erythropoietin (EPO) values were markedly lower in athletes than in controls, and 58% had EPO lower than the detection limit for the assay. This may be due to high-altitude residence prior to testing. Measurements of growth hormone (GH) and insulin-like growth factor 1 did not suggest GH-misuse in any athlete tested. One third of the male athletes had testosterone levels that were lower than the normal reference interval. This may at least partly be due to the combination of sampling at night and after strenuous exercise. One female athlete was found to have a grossly elevated testosterone level. In conclusion, the present results show the importance of taking into account the special circumstances during sampling when interpreting results from blood testing in athletes. Future research should focus on developing more sensitive and specific tests to detect doping with endogenous substances such as GH and EPO.

Urinary testosterone (T) to epitestosterone (E) ratios by GC/MS. I. Initial comparison of uncorrected T/E in six international laboratories.

Six laboratories in six countries collaborated to investigate the analytical method for estimating the testosterone to epitestosterone ratio (T/E) in urine by gas chromatography/mass spectrometry in the context of detecting the application of T as a doping agent in sport. The protocol specified many but not all details of reagents and instrument conditions. The design included the distribution and analysis of four urines with different T/E values, three replicates per value, and one standard. The ranges of mean T/E values for the four urines estimated by peak area (PA) were 0.32-0.42, 0.72-0.94, 0.91-1.14 and 3.19-5.48. The analyses of variance for these data and for the peak height (PH) data were significant for the laboratory factor (p < 0.0001). In addition there was a significant interaction between the urine factor and the laboratory factor which indicates the complexity of the analysis. T/E calculated using PA was not significantly different from that using PH. For within-laboratory precision all values for PH and PA were < 8.3%, and for between-laboratory precision all values were < 11.7% except for one (20.1%). The data represent a baseline for future experiments designed to elucidate the sources of within-and between-laboratory variance, and to harmonize estimates of T/E.

Effect on sports drug tests of ingesting meat from steroid (methenolone)-treated livestock.

Anabolic-androgenic steroids are widely misused in human sports and are also used as growth promoters in livestock. Athletes who consume meat containing such hormone residues may risk failing a sports drug test. Prompted by an athlete's defense case, we questioned whether the consumption of small livestock given doses of anabolic steroid, orally or intramuscularly, could generate positive results in samples tested by our analytical procedures. We analyzed urine from eight men who consumed chickens that had been either fed with methenolone acetate (1 mg/day) from day 0 to 21 or injected with methenolone heptanoate depot (1 mg/intramuscular injection) on days 0, 7, and 14 and slaughtered on day 22. No methenolone or characteristic major metabolite was detected in samples from subjects who ate meat from the orally dosed chickens. However, 50% of the samples collected 24 h after consumption of the intramuscularly dosed chickens were confirmed positive. Hence, eating meat containing small amounts of injected hormone may constitute a serious liability to the athlete.

Establishing a ketoconazole suppression test for verifying testosterone administration in the doping control of athletes.

The ratio of urinary testosterone (u-T) to epitestosterone (T/EpiT) is used to disclose testosterone (T) administration in the doping control of sports, and a ratio greater than 6 constitutes an offence. Nevertheless, the possibility of biological outliers must not be discounted, and the use of ketoconazole has been suggested for a dynamic test to distinguish between such athletes and those using T. In this investigation, ketoconazole was administrated to three groups of T-pretreated and two groups of untreated healthy male subjects. The subjects in one of the pretreated groups were patients with mild hypogonadism. One untreated group consisted of athletes that had been tested three times with high urinary T/EpiT levels. The effects of ketoconazole administration on serum T (s-T) level and urinary T/EpiT ratio were monitored every 2 h for an 8-h period and clearly separated T-pretreated and untreated subjects into two clusters (P < 0.0001). The T/EpiT ratio increased and the s-T level remained unchanged in pretreated individuals during the ketoconazole test, whereas T/EpiT decreased by 60% and s-T by almost 90% in untreated subjects. The statistical power of the test increased by using several time points and combining the urinary T/EpiT with the s-T data. In conclusion, the ketoconazole test is suitable as a supportive dynamic test for the urinary T/EpiT ratio measurements in the doping control of athletes.

Potential use of ketoconazole in a dynamic endocrine test to differentiate between biological outliers and testosterone use by athletes.

Determination of the ratio of testosterone to epitestosterone (T/E) in urine is used to detect testosterone administration in athletes, with a ratio > 6 considered as evidence of an offense. We show that administration of ketoconazole, which inhibits testosterone biosynthesis, may be useful for differentiating between an athlete who is using testosterone and one who naturally gives a ratio > 6. In a control subject pretreated with testosterone, ketoconazole caused the ratio to increase; conversely, it caused a decrease in the ratio in an athlete under investigation. Repeated administration of ketoconazole to two normal men caused a decrease in the ratio due to a large decrease in the urinary excretion rate of testosterone relative to epitestosterone. Stimulation with human chorionic gonadotropin exacerbated the differences in excretion rates. A single administration of ketoconazole to six normal men caused the T/E ratios to decrease significantly within 8 h, a suitable time scale for use in a dynamic test.

[Doping and doping control in Norway]. / Doping og dopingkontroll i Norge.

Misuse of drugs and methods of doping in connection with various physical activities have become serious problems for sports organizations and may seriously impair the health of the misusers. The Norwegian Confederation of Sports has banned doping, and carries out doping controls at competitions as well as out-of-competition tests. Doping controls and laboratory analyses are performed according to approved procedures. An athlete who is found guilty of doping will be excluded from organized sport for a specified period of time. Doctors have a special duty to keep themselves updated on the doping problem, and support the anti-doping work by their own practices.

Detection of testosterone administration by increased ratio between serum concentrations of testosterone and 17 alpha-hydroxyprogesterone.

An increased ratio between urinary testosterone (T) and epitestosterone (epiT) has been accepted by the International Olympic Committee as a marker for T doping. However, in a few subjects, we and others have observed constantly above-normal urinary T/epiT ratios that are unlikely to be related to exogenous T administration. To find a better test for T doping, we studied several serum and urinary androgens and androgen precursors, estrogens, and luteinizing hormone (LH) in seven healthy volunteers for 35 days after an intramuscular injection of 250 mg of testosterone enanthate. Among urinary analyses, only the T/epiT ratio was a suitable marker of T doping; of the serum assays, 17 alpha-hydroxyprogesterone (17OHP), T/17OHP ratio, LH, and T/LH ratio were fair to good markers of T doping. The serum T/17OHP ratio was the best marker of those tested, with all seven subjects having above-normal values for this in the first 3 days of the observation period. No other marker showed abnormal values in all subjects at any time. Moreover, the T/17OHP ratio was affected by neither diurnal variation nor physical stress. The value of this marker for T doping was further supported by the finding of normal T/17OHP ratios in a subject with increased urinary T/epiT ratios caused by an abnormally low testicular epiT production, probably related to genetic factors.

Comparison of changes in testosterone concentrations after strength and endurance exercise in well trained men.

Changes in the testosterone concentrations after single sessions of endurance and strength training were measured in seven well trained men, experienced in both forms of training. Both training sessions were rated as hard to very hard on the Borg scale. Blood samples for testosterone measurements were taken before, immediately after, and 2, 4 and 6 h after the training sessions as well as the next morning. The mean testosterone concentration increased 27% (P less than 0.02) and 37% (P less than 0.02) during the strength and endurance training session, respectively. Two hours after the training sessions the mean testosterone concentration had returned to the pre-training level and remained at that level for the length of the observation period. There were no significant differences in the changes in testosterone concentration after strength and endurance training but there were large differences in the testosterone response at the level of the individual. A high correlation (r = 0.98; P less than 0.001) for individuals was found between increases in testosterone concentration after strength and after endurance training. It was concluded that the changes in mean testosterone values followed the same timecourse after single sessions of strength and endurance training of the same duration and perceived exertion. The interindividual differences in testosterone response may be of importance for individual adaptation to training.

Reconstitution of C27-steroid 26-hydroxylase activity from bovine brain mitochondria.

We have previously demonstrated the presence of cytochrome P-450 in a soluble preparation of bovine brain mitochondria (Oftebro, H., Størmer, F.C., and Pedersen, J.I. (1979) J. Biol. Chem. 254, 4331). In the present work we show that this preparation, in the presence of NADPH, adrenodoxin and adrenodoxin reductase catalyzes omega-hydroxylation of a number of C27-steroids that are intermediates in bile acid biosynthesis. The rates of hydroxylation were 1-2 order of magnitudes lower than reported for similar preparations from rat and human liver. No significant activity was detected with cholesterol as substrate. The physiological significance of brain mitochondrial cytochrome P-450 is discussed.

Validation of a radioreceptor assay for 1,25-dihydroxyvitamin D using selected ion monitoring GC-MS.

This report describes two methods for the measurement of 1,25-dihydroxyvitamin D [1,25(OH)2D] in serum: A modified radio receptor assay (RRA), employing a 1,25(OH)2D receptor from calf thymus, and selected ion monitoring (SIM) with combined capillary gas chromatography (GC)-mass spectrometry (MS). The intra-assay coefficient of variation was close to 13% for both methods, and the inter-assay coefficients of variation were 14.0 and 6.5% for RRA and SIM (GC-MS), respectively. Aliquots of 2 ml (RRA) and 20 ml (SIM) serum were used, and the limits of detection were 10 and 6 pmol/l, respectively. The analytical recovery of each method was assessed, and a maximum deviation from the expected value of 10 and 2% was found for RRA and SIM, respectively. A correlation coefficient of 0.93 (slope 0.97) was obtained when 27 different serum samples were analyzed by both methods. Included in this study were serum samples from healthy subjects and patients with subnormal as well as supranormal 1,25(OH)2D levels. This result showed that the RRA accurately measured the serum levels of 1,25(OH)2D and therefore should be useful in the diagnosis and control of vitamin D dependent diseases.

Calcium status and calcium-regulating hormones in alcoholics.

To elucidate effects of chronic ethanol consumption on clinical chemical parameters reflecting overall calcium homeostasis 34 hospitalized male alcoholics and 35 age-matched controls were studied during the winter season. Serum concentrations of 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 were reduced by 28% (p less than 0.01) and 24% (p less than 0.02) among the alcoholics as compared to the controls, respectively. Dietary intake of vitamin D3 did not differ significantly between the groups. The calcium level was below lower limit of reference in nine alcoholics (26%). Serum concentrations of parathyroid hormone and phosphorus were within normal ranges in both groups, and no differences were observed in levels of magnesium, vitamin D-binding protein, calcitonin, or alkaline phosphatase. In conclusion, it is possible that the activities of enzymes crucial in vitamin D3 metabolism may be altered in alcoholics.

Biochemical changes and endocrine responses in cystic fibrosis in relation to incremental maximal exhaustive exercise.

The purpose of this study was to compare biochemical changes and endocrine responses during an incremental maximal bicycle test in three well-trained 18-year-old patients with cystic fibrosis (CF) and in three healthy controls. Although the blood concentration at rest of the white cell count, haptoglobin, phosphorus, urea, creatinine, and uric acid were somewhat different in the two groups, the CF patients had similar biochemical changes in response to the exercise compared with the healthy men. The endocrine responses to exercise seemed to be different between the two groups with regard to changes in cortisol, growth hormone, and testosterone concentrations. The differences, however, were probably caused by differences in age, training situation, and psychological stress reaction rather than by pathological mechanisms.

Biochemical changes and endocrine responses in cystic fibrosis in relation to a marathon race.

Biochemical changes and endocrine responses during the New York Marathon (42195 m) were investigated in three 18-year-old male adolescents with cystic fibrosis (CF) and three healthy men who accompanied the CFs during the race. The ambient temperature was 20 degrees-28 degrees C and the relative humidity 98%-75% during the run. The CF patients, who had Shwachman scores of 60, 85 and 95 completed the run without major problems in 6.10, 4.42, and 4.32 h, respectively. Serum concentrations of Na and Cl decreased slightly, but the values were still within normal range. Na and Cl excretions in the urine decreased to very low levels in the CF adolescents during the run. All the other biochemical changes were similar to the changes in the controls. Aldosterone concentration increased to a higher level and maintained this increase for a longer time after the race in the CFs. Testosterone concentration decreased more in the CFs during the race compared with the controls. Growth hormone concentration showed individually varying changes in response to the exercise. This study demonstrates that patients with CF may participate in strenuous prolonged exercise even in humid and hot conditions, without untoward effects. The observed differences in hormonal responses to exercise might be explained by differences in age, training status, and relative exercise intensity rather than by hormonal or other disturbances in CF.

Vigorous exercise in a female with cystic fibrosis: spirometric, biochemical, and endocrine responses during four types of intensive exercise.

Spirometric, biochemical, and endocrine responses during a maximal ergometer cycle test and during three runs (10 km, 21.1 km, and 42.2 km) were investigated in one female with cystic fibrosis (CF) 27 years of age and in two healthy control females 26 and 29 years of age. One of the controls ran as a companion to the CF woman, while the other ran at her own speed. The CF woman has a chronic respiratory Pseudomonas aeruginosa infection, and her spirometric values were 50%-70% of predicted values at the time of the study. For the last years she has been training almost daily with aerobics, running, cycling, or skiing. She completed the four types of exercise without major problems. Her spirometric values increased transiently following the cycle test and for several hours following the three races (maximal 20%-30% increase of spirometric values), while the controls had transient decreases of the same variables in response to the runs. The biochemical and the hormonal changes were similar in the CF woman and the control who ran at her own speed, while the control who was a less stressed companion showed smaller changes. This study demonstrates that well-trained females with CF may participate in strenuous prolonged exercise without untoward effects.