Effect of 12-months testosterone replacement therapy on bone mineral density and markers of bone turnover in testicular cancer survivors - results from a randomized double-blind trial.

BACKGROUND: Testicular cancer survivors (TCS) are at risk of Leydig cell insufficiency, which is a condition characterized by elevated luteinising hormone (LH) in combination with low levels of testosterone. It has been suggested that this condition is associated with impaired metabolic profile and low bone mineral density (BMD). The primary aim of the randomized double-blind trial NCT02991209 was to evaluate metabolic profile after 12-months testosterone replacement therapy (TRT) in TCS with mild Leydig cell insufficiency. Here we present the secondary outcomes of changes in BMD and markers of bone turnover. METHODOLOGY: In total, 69 TCS with mild Leydig cell insufficiency were randomized 1:1 to 12 months TRT (n = 35) (Tostran, gel, 2%, applied transdermally, with a maximum daily dose of 40 mg) or placebo (n = 34). BMD and markers of bone turnover were evaluated at baseline, after 6- and 12-months TRT, and 3-months post-treatment. Linear mixed effects models were used to analyse changes in BMD, N-terminal propeptide of type 1 procollagen (P1NP) and C-terminal telopeptide of type I collagen (CTX). RESULTS: After 12 months treatment, TRT was not associated with a statistically significant difference in BMD compared to placebo; total body BMD: 0.01 g/cm2 (95% confidence interval (CI): -0.01 - 0.02), BMD of the lumbar spine: 0.01 g/cm2, (95% CI: -0.01-0.03), BMD of the left femoral neck: 0.00, (95% CI: -0.01-0.02). TRT was associated with a small but statistically significant increase in P1NP: 11.65 µg/L (95% CI: 3.96, 19.35), while there was no difference in CTX. CONCLUSION: 12 months of TRT did not change BMD, while there was as small and clinically irrelevant increase in P1NP compared to placebo in TCS with mild Leydig cell insufficiency. The findings need validation in a larger cohort.

Baseline bone turnover marker levels can predict change in bone mineral density during antiresorptive treatment in osteoporotic patients: the Copenhagen bone turnover marker study.

Anti-resorptive osteoporosis treatment might be more effective in patients with high bone turnover. In this registry study including clinical data, high pre-treatment bone turnover measured with biochemical markers was correlated with higher bone mineral density increases. Bone turnover markers may be useful tools to identify patients benefitting most from anti-resorptive treatment. INTRODUCTION: In randomized, controlled trials of bisphosphonates, high pre-treatment levels of bone turnover markers (BTM) were associated with a larger increase in bone mineral density (BMD). The purpose of this study was to examine this correlation in a real-world setting. METHODS: In this registry-based cohort study of osteoporosis patients (n = 158) receiving antiresorptive therapy, the association between pre-treatment levels of plasma C-telopeptide of type I Collagen (CTX) and/or N-terminal propeptide of type I procollagen (PINP) and change in bone mineral density (BMD) at lumbar spine, total hip, and femoral neck upon treatment was examined. Patients were grouped according to their pre-treatment BTM levels, defined as values above and below the geometric mean for premenopausal women. RESULTS: Pre-treatment CTX correlated with annual increase in total hip BMD, where patients with CTX above the geometric mean experienced a larger annual increase in BMD (p = 0.008) than patients with CTX below the geometric mean. The numerical pre-treatment level of CTX showed a similar correlation at all three skeletal sites (total hip (p = 0.03), femoral neck (p = 0.04), and lumbar spine (p = 0.0003)). A similar association was found for PINP where pre-treatment levels of PINP above the geometric mean correlated with a larger annual increase in BMD for total hip (p = 0.02) and lumbar spine (p = 0.006). CONCLUSION: Measurement of pre-treatment BTM levels predicts osteoporosis patients' response to antiresorptive treatment. Patients with high pre-treatment levels of CTX and/or PINP benefit more from antiresorptive treatment with larger increases in BMD than patients with lower pre-treatment levels.

Bone microarchitecture and bone mineral density in multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) patients are at increased risk of reduced bone mineral density (BMD) and fractures. The aetiology of bone loss in MS is unclear. Trabecular bone score (TBS) is a novel analytical tool that provides a measurement of the bone microarchitecture. Decreased TBS predicts increased fracture risk independently of BMD. To date, no studies have investigated TBS in MS patients. OBJECTIVES: To assess bone quality in MS patients by TBS and to evaluate potential risk factors that may affect BMD and TBS in patients with MS. METHODS: Two hundred sixty MS patients were included. TBS was calculated using TBS iNsight software (MediMaps® ). Multivariable regression analyses were performed with information on smoking, alcohol, glucocorticoid (GC) treatment, sun exposure, physical activity, vitamin D and BMI. RESULTS: Trabecular bone score was not significantly different from an age-matched reference population. Low TBS was associated with high age (P = .014) and smoking (P = .03). Smoking and physical inactivity were associated with low BMD in spine (P = .034, P = .032). GC treatment was not associated with TBS. CONCLUSION: We could not find altered TBS values among MS patients, suggesting that BMD alone, and not the bone microarchitecture, is affected in MS. However, larger studies are needed to verify these findings and to establish the role of TBS in MS. As in the background population, physical activity and non-smoking habits are associated with better bone health in MS.

Leydig cell dysfunction, systemic inflammation and metabolic syndrome in long-term testicular cancer survivors.

BACKGROUND: Twenty to thirty percent of testicular cancer (TC) survivors have elevated serum levels of luteinising hormone (LH) with or without corresponding low testosterone levels (Leydig cell dysfunction) during clinical follow-up for TC. However, it remains to be clarified if this subgroup of TC survivors has an increased long-term risk of systemic inflammation and metabolic syndrome (MetS) when compared with TC survivors with normal Leydig cell function during follow-up. PATIENTS AND METHODS: TC survivors with Leydig cell dysfunction and a control group of TC survivors with normal Leydig cell function during follow-up were eligible for participation in the study. Markers of systemic inflammation and prevalence of MetS were compared between TC survivors with Leydig cell dysfunction and the control group. RESULTS: Of 158 included TC survivors, 28 (18%) had uncompensated Leydig cell dysfunction, 59 (37%) had compensated Leydig cell dysfunction and 71 (45%) had normal Leydig cell function during follow-up. MetS and markers of systemic inflammation were evaluated at a median follow-up of 9.7 years (interquartile range 4.1-17.1) after TC treatment. The prevalence of MetS was significantly lower among patients with compensated Leydig cell dysfunction during follow-up (12% versus 27%, p = 0.04), whereas there was no difference between TC survivors with uncompensated Leydig cell dysfunction and controls (33% versus 27%, p = 0.5). Apart from high-sensitivity C-reactive protein which was higher in TC survivors with uncompensated Leydig cell dysfunction during follow-up, there was no evidence of increased systemic inflammation in patients with Leydig cell dysfunction during clinical follow-up. Total testosterone at follow-up was significantly associated with MetS, whereas there was no association between LH and MetS. CONCLUSION: We did not find evidence that TC survivors with Leydig cell dysfunction during clinical follow-up had increased long-term risk of MetS. Total testosterone at follow-up was significantly associated with MetS. The study is registered at www.clinicaltrials.govNCT02240966.

Reproductive hormones and metabolic syndrome in 24 testicular cancer survivors and their biological brothers.

Testicular cancer survivors have impaired gonadal function and increased risk of metabolic syndrome when compared to healthy controls. However, because of the fetal etiology of testicular cancer, familial unrelated healthy men might not be an optimal control group. The objective of this study was to clarify if testicular cancer survivors have impaired gonadal function and increased risk of metabolic syndrome when compared to their biological brothers. A cross-sectional study of testicular cancer survivors (ClinicalTrials.gov number, NCT02240966) was conducted between 2014 and 2016. Of 158 testicular cancer survivors included, 24 had a biological brother who accepted to participate in the study. Serum levels of reproductive hormones and prevalence of metabolic syndrome according to International Diabetes Federation Criteria and National Cholesterol Education Program (Adult Treatment Panel III) criteria comprised the main outcome measures of the study. Median age was similar in testicular cancer survivors and their biological brothers [44 years (IQR 39-50) vs. 46 (40-53) years respectively (p = 0.1)]. In testicular cancer survivors, follow-up since treatment was 12 years (7-19). Serum levels of luteinizing hormone and follicle-stimulating hormone were elevated (p ≤ 0.001), while total testosterone, free testosterone, inhibin B and anti-Müllerian hormone were lower (p ≤ 0.001) in testicular cancer survivors than in their biological brothers. The prevalence of metabolic syndrome was similar and apart from HDL-cholesterol, which was lower in testicular cancer survivors (p = 0.01); there were no differences in the individual components of the metabolic syndrome between testicular cancer survivors and their brothers. In conclusion, gonadal function was impaired in testicular cancer survivors, while we did not detect any difference in the prevalence of metabolic syndrome between testicular cancer survivors and their biological brothers.

Forty-five-year follow-up on the renal function after spinal cord injury.

STUDY DESIGN: Retrospective chart review. OBJECTIVES: To investigate the extent of renal deterioration in patients with spinal cord injury (SCI) and to identify risk indicators associated with renal deterioration. SETTING: Clinic for Spinal Cord Injuries, Rigshospitalet, Hornbæk, Denmark. METHODS: This study included 116 patients admitted to our clinic with a traumatic SCI sustained between 1956 and 1975. Results from renography and (51)Cr-EDTA plasma clearance were collected from medical records from time of injury until 2012, and the occurrence of renal deterioration was analysed by cumulative incidence curves. The impact of demographics, neurological level and completeness of SCI, urinary tract stones, dilatation of the upper urinary tract (UUT) and bladder-emptying methods were analysed with Cox proportional hazard ratios. RESULTS: The bladder-emptying methods used for the longest period were reflex triggering (63%), bladder expression (22%), indwelling catheter (5%), normal voiding (4%), ileal conduit (3%) and clean intermittent catheterisation (2%). The cumulative risk of moderate renal deterioration (functional distribution outside 40-60% on renography or relative glomerular filtration rate (GFR) ⩽75% of expected according to age and gender) was 58%. The cumulative risk of severe renal deterioration (functional distribution outside 30-70% on renography or relative GFR⩽51%) was 29% after 45 years postinjury. Only dilatation of UUT and renal/ureter stone requiring removal significantly increased the risk of moderate and severe renal deterioration. CONCLUSION: Renal deterioration occurs at any time after injury, suggesting that lifelong follow-up examinations of the renal function are important, especially in patients with dilatation of UUT and/or renal/ureter stones.

Short-term, high-dose glucocorticoid treatment does not contribute to reduced bone mineral density in patients with multiple sclerosis.

BACKGROUND: Patients with multiple sclerosis (MS) are at increased risk of reduced bone mineral density (BMD). A contributing factor might be treatment with high-dose glucocorticoids (GCs). OBJECTIVES: The objective of this paper is to assess bone mass in patients with MS and evaluate the importance of short-term, high-dose GC treatment and other risk factors that affect BMD in patients with MS. METHODS: A total of 260 patients with MS received short-term high-dose GC treatment and had their BMD measured by dual x-ray absorptiometry. BMD was compared to a healthy age-matched reference population (Z-scores). Data regarding GCs, age, body mass index (BMI), serum 25(OH)D, disease duration and severity were collected retrospectively and analysed in a multiple linear regression analysis to evaluate the association between each risk factor and BMD. RESULTS: Osteopenia was present in 38% and osteoporosis in 7% of the study population. Mean Z-score was significantly below zero, indicating a decreased BMD in our MS patients. Multiple linear regression analysis showed no significant association between GCs and BMD. In contrast, age, BMI and disease severity were independently associated with both lumbar and femoral BMD. CONCLUSION: Reduced BMD was prevalent in patients with MS. GC treatment appears not to be the primary underlying cause of secondary osteoporosis in MS patients.

50 years follow-up on plasma creatinine levels after spinal cord injury.

STUDY DESIGN: Retrospective chart review. OBJECTIVES: To investigate the role of plasma creatinine (p-creatinine) in monitoring renal deterioration in patients up to 50 years after spinal cord injury (SCI). SETTING: The Clinic for Spinal Cord Injuries, Rigshospitalet, Denmark. METHODS: A total of 119 patients with a traumatic SCI during the years 1944-1975 were included in the study. P-creatinine measurements, results from renography and glomerular filtration rate (GFR) measured with 51Cr-EDTA clearance were obtained from medical records and analyzed using a linear mixed model and linear regression analyses. RESULTS: When compared with median p-creatinine level in the first 5-year period after injury, the level of p-creatinine was stable throughout the first 30 years and decreased significantly after the 30th until 45th year post injury. Only patients with a functional distribution outside the 30-70% limits on renography or a relative GFR < or =51% of that expected had a significantly elevated level of p-creatinine. Significance was not found for patients with a distribution outside the 40-60% limits on renography or relative GFR < or =75%. By comparing Cr-EDTA clearance and p-creatinine in terms of exceeding the upper reference level, p-creatinine revealed 17% sensitivity, 100% specificity, 100% positive predictive value and 73% negative predictive value as a diagnostic test for renal deterioration defined as GFR < or =75%. CONCLUSION: P-creatinine decreases over time in patients with SCI with a level below the upper reference limit and is a poor detector of early renal deterioration in patients with SCI.

Prostaglandin E2(PGE2) induces headache in healthy subjects.

The role of prostanoids in nociception is well established. The headache-eliciting effects of prostaglandin E(2) (PGE(2)) and its possible mechanisms have previously not been systematically studied in man. We hypothesized that infusion of PGE(2) might induce headache and vasodilation of cranial vessels. PGE(2) (0.40 microg kg(-1) min(-1)) or saline was infused for 25 min into 11 healthy subjects in a cross-over, double-blind study. Headache intensity was scored on a verbal rating scale from 0 to 10. In addition, we recorded mean flow in the middle cerebral artery (V(MCA)) by transcranial Doppler and diameter of the superficial temporal artery (STA) by high-resolution ultrasonography. All 11 subjects reported headache on the PGE(2) day and no subjects reported headache on the placebo day (P = 0.001). During the immediate phase (0-30 min) (P = 0.005) and the postinfusion phase (30-90 min) (P = 0.005), the area under the curve for headache score was significantly larger on the PGE(2) day compared with the placebo day. PGE(2) caused dilatation of the STA (23.5%; 95% CI 14.0, 37.8) and the MCA (8.3%; 95% CI 4.0, 12.6). We suggest that PGE(2) induces headache by activation and sensitization of cranial perivascular sensory afferents.

The cholinomimetic agent carbachol induces headache in healthy subjects.

The parasympathetic nervous system is likely to be involved in migraine pathogenesis. We hypothesized that the cholinomimetic agonist carbachol would induce headache and vasodilation of cephalic and radial arteries. Carbachol (3 microg/kg) or placebo was randomly infused into 12 healthy subjects in a double-blind crossover study. Headache was scored on a verbal rating scale from 0-10. Velocity in the middle cerebral artery (V(MCA)) and diameter of the superficial temporal artery (STA) and radial artery (RA) were recorded. Nine participants developed headache after carbachol compared with three after placebo. The area under the curve for headache was increased after carbachol compared with placebo both during infusion (0-30 min) (P = 0.042) and in the postinfusion period (30-90 min) (P = 0.027). Carbachol infusion caused a drop in V(MCA) (P = 0.003) and an increase in STA diameter (P = 0.006), but no increase in the RA diameter (P = 0.200). In conclusion, the study demonstrated that carbachol caused headache and dilation of cephalic arteries in healthy subjects.

Evaluation of Tc-99m-tetrofosmin single-photon emission computed tomography for detection of chronic exertional compartment syndrome of the leg.

Chronic exertional compartment syndrome (CECS) of the leg is a common, painful condition related to exercise and associated with increased muscle compartment pressure (CP). Invasive methods are currently the method of choice for diagnosing the condition. We investigated the use of Tc-99m-tetrofosmin perfusion single-photon emission computed tomography (SPECT) as a diagnostic tool compared with the gold standard, muscle CP measurement. In 14 subjects perfusion SPECT and CP were measured before and immediately after exercise leading to pain in the lower legs. Six subjects had increased pressures indicating the presence of CECS. In three (50%) of these muscular hypoperfusion was observed by perfusion SPECT. In eight subjects with normal CPs SPECT suggested muscular hypoperfusion. Because of the low diagnostic rates, sensitivity 50% and specificity 63%, Tc-99m-tetrofosmin perfusion SPECT seems not to be a useful method for diagnosing CECS.

Vasoactive intestinal polypeptide evokes only a minimal headache in healthy volunteers.

The role of the parasympathetic nervous system in the pathogenesis of migraine is disputed. The headache-eliciting effect of the parasympathetic neurotransmitter, vasoactive intestinal polypeptide (VIP), and its effect on cerebral arteries and brain haemodynamics has not been systematically studied in man. We hypothesized that infusion of VIP might induce headache in healthy subjects and cause changes in cerebral haemodynamics. VIP (8 pmol/kg per min) or placebo (0.9% saline) was infused for 25 min into 12 healthy young volunteers in a crossover, double-blind design. Headache was scored on a verbal rating scale from 0 to 10, regional cerebral blood flow (rCBF) was measured with single-photon emission computed tomography and (133)Xe inhalation and mean flow velocity in the middle cerebral artery (V(meanMCA)) was measured with transcranial Doppler ultrasonography. The headache was very mild with a maximum score of 2 and described as a pressing or throbbing sensation. Five participants developed headache during VIP and one during placebo. During the infusion, a significant drop in V(meanMCA) was seen for VIP compared with placebo (P < 0.001), but the effect quickly waned and no difference was found when comparing the time between 30 and 120 min. In addition, no significant difference in the diameter of the MCA could be found during the infusion. No significant differences in rCBF (P = 0.10) were found between VIP and placebo. A marked dilation of the superficial temporal artery was seen (P = 0.04) after VIP in the first 30 min but no difference was found when comparing the time between 30 and 120 min. We found no difference in mean arterial blood pressure between VIP and placebo days but the heart rate increased significantly on a VIP day compared with a placebo day (AUC(0-30 min), P < 0.001). Plasma VIP was significantly higher on a VIP day compared with placebo (AUC(0-80 min), P < 0.001). These results show that VIP causes a decrease in V(meanMCA) without affecting rCBF. In spite of a marked vasodilator effect in the extracranial vessels and increased plasma VIP, healthy subjects developed only a very mild headache.

Effects of advanced glycation end-product inhibition and cross-link breakage in diabetic rats.

The accelerated formation of advanced glycation end-products (AGEs) due to elevated glycemia has repeatedly been reported as a central pathogenic factor in the development of diabetic microvascular complications. The effects of a novel inhibitor of AGE formation, NNC39-0028 (2,3-diaminophenazine), and a breaker of already formed AGE cross-links, N-phenacylthiazolium bromide (PTB), were investigated in streptozotocin-diabetic female Wistar rats. Diabetes for 24 weeks resulted in decreased tail collagen pepsin solubility, reflecting the formation of AGE cross-linking. Collagen solubility was significantly ameliorated by treatment with NNC39-0028, whereas PTB had no effect. Increased urinary albumin excretion (UAE) in diabetic rats was observed in serial measurements throughout the study period, and was not reduced by any treatment. Vascular dysfunction in the eye, measured as increased clearance of 125I-albumin, was induced by diabetes. NNC39-0028 did not affect this abnormality. This study demonstrated a pharmacological inhibition of collagen solubility alterations in diabetic rats without affecting diabetes-induced pathophysiology such as the increase in UAE or albumin clearance. Treatment with PTB, a specific breaker of AGE cross-links, had no effects in this study.

Effects of heparin on vascular dysfunction in diabetic rats.

1. Treatment with heparin has beneficial effects in diabetic nephropathy. The occurrence of increased urinary albumin excretion in diabetic patients reflects general vascular dysfunction, including increased transcapillary permeability of macromolecules. The aim of the present study was to evaluate the effects of heparin on vascular dysfunction in diabetic rats. 2. Male Sprague-Dawley rats were used in two studies. Diabetes was induced by 65 mg/kg, i.v., streptozotocin. In one study, diabetic rats were dosed subcutaneously with different heparin fractions for 8 months and the transcapillary escape rate of albumin (TERalb) was measured in anaesthetized animals. In the other study, heparin was given for 6 weeks, followed by tissue albumin clearance measurements in awake rats. Normal and diabetic rats receiving saline served as controls. 3. Blood glucose did not differ among the diabetic groups and ranged from 22 to 26 mmol/L. The mean (+/- SD) TERalb was increased by diabetes compared with values in normal rats (17.5 +/- 3 vs 14.1 +/- 3.3%/h, respectively). Neither unfractionated nor low molecular weight heparin significantly affected this increase. [131I]-Albumin clearance was significantly increased in diabetic rats in the eye, skin and skeletal muscle tissues compared with normal rats (0.17-0.40 vs 0.1-0.23 microL plasma/g per min). Low molecular weight heparin treatment did not affect the increased organ albumin clearance. 4. In conclusion, heparin treatment does not affect diabetes-induced vascular dysfunction as expressed by increased TERalb and clearance of albumin in rats.

Proteoglycan expression in the normal rat kidney.

Proteoglycans constitute a heterogenous group of complex macromolecules, consisting of a backbone core protein and a variable number of sulfated polysaccharide side chains covalently linked to the core. A dual function for these polyanionic glycosaminoglycans in kidney physiology has been proposed: to maintain a fixed negative charge in the glomerular filtration barrier, and to bind and sequester cytokines essential for renal development and function. With the aim of identifying proteoglycan genes expressed in kidney glomeruli, we have performed in situ hybridization for selected proteoglycan core proteins in the normal rat kidney. Syndecan-4, glypican-1 and biglycan were all expressed in normal glomeruli, whereas syndecan-1, perlecan and versican mRNAs were confined to the papillary area. Decorin mRNA was detected in interstitial cells found between tubuli and surrounding larger vessels. No signal for betaglycan mRNA could be detected. By hybridizing adjacent sections with a probe for the podocyte-specific PTPase GLEPP-1, the glomerular cells containing mRNA for syndecan-4 and glypican-1 could be identified as podocytes, whereas the cells expressing biglycan were identified as mesangial cells. These results demonstrate that seven out of the eight proteoglycans investigated are expressed in the normal kidney in detectable amounts and, importantly, that each proteoglycan gene shows a unique pattern of expression. The constitutive expression of syndecan-4, glypican-1 and biglycan in glomerular cells points to a role for these polyanionic molecules in maintaining the integrity of the glomerular filtration barrier.

Effects of heparin and aminoguanidine on glomerular basement membrane thickening in diabetic rats.

The effects of heparin and aminoguanidine on glomerular basement membrane thickening were studied in streptozotocin diabetic Sprague-Dawley rats. A placebo-treated group and a non-diabetic group served as controls. All diabetic rats remained severely hyperglycaemic (23 mmol/l) throughout the 8-month study period. At the end of this time relative kidney weight was significantly increased in diabetic control rats (4.9 +/- 0.5 g/kg b.w.) compared with non-diabetic rats (3.3 +/- 0.3 g/kg). This increase was not affected by the intervention treatments. Glomerular basement membrane thickness increased 32% in diabetic control rats (240 +/- 24 nm) compared with non-diabetic rats (182 +/- 20 nm). This increase was prevented by s.c. treatment with both unfractionated and low molecular weight heparins, while basement membrane thickness was the same in animals treated with oral heparins and aminoguanidine and untreated diabetic rats. Macroscopic malignant kidney tumours were seen in three aminoguanidine-treated rats. In conclusion, subcutaneously administered heparin prevents diabetes-induced glomerular basement membrane thickening.

Ceftriaxone versus latamoxef in febrile neutropenic patients: empirical monotherapy in patients with solid tumours.

121 patients with 132 febrile episodes were randomised to ceftriaxone or latamoxef monotherapy in order to compare antibiotic efficacy in neutropenic patients treated with cytotoxic chemotherapy for solid tumours. In 80 evaluable episodes no significant differences were observed between the two groups with respect to efficacy and fatal failure rates. Of episodes treated with ceftriaxone, 67% showed a favourable clinical response vs. 61% in the latamoxef group. The clinical response rates in episodes with documented bacterial infections were 67 and 56% in the two treatment groups. In 18% of the episodes with documented initial infections the patients died of presumably uncontrolled infection. The convenient once daily dosage schedule combined with fewer severe adverse reactions favours the use of ceftriaxone instead of latamoxef. Although a relative high degree of response was seen, empirical antibiotic monotherapy apparently does not offer a sufficient antibacterial cover in infections in this type of patient with defective host immunity.

Effects of thyrotropin-releasing hormone on regional cerebral blood flow in man.

To assess the regional changes in cerebral blood flow, 10 healthy volunteers were given 400 micrograms thyrotropin-releasing hormone iv in a double-blind, randomized, cross-over study. Regional cerebral blood flow was determined simultaneously in two slices of the brain, using a single photon emission computerized tomograph and inhalation of 133Xe. Thyrotropin-releasing hormone caused a significant mean increase of 3.7% (range -8.8-22.7) in blood flow in a region consistent with the left thalamus compared to placebo (3.2% decrease). In 25 other regions no significant change was detected. The thalamic region has previously been shown to be a region especially affected by thyrotropin-releasing hormone in animal studies. The thyrotropin-releasing hormone injection was followed by a minor rise in systemic blood pressure, but not a rise that could affect the cerebral blood flow. The effect of thyrotropin-releasing hormone on the regional cerebral blood flow in the thalamic region was much lower compared to changes found in sedated animals given a hundredfold higher dose of thyrotropin-releasing hormone.