Effects of surgery on plasma levels of cortisol, corticosterone and non-protein-bound-cortisol

ABCC1 modulates negative feedback control of the hypothalamic-pituitary-adrenal axis in vivo in humans

BACKGROUND

Cortisol and corticosterone both circulate in human plasma and, due to differing export by ATP-binding cassette (ABC) transporters, may exert differential cellular effects. ABCB1 (expressed in brain) exports cortisol not corticosterone while ABCC1 (expressed in adipose and skeletal muscle) exports corticosterone not cortisol. We hypothesised that ABCC1 inhibition increases corticosteroid receptor occupancy by corticosterone but not cortisol in humans.

METHODS

A randomised double-blind crossover study was conducted in 14 healthy men comparing placebo and ABCC1 inhibitor probenecid. Blood sampling, including from veins draining adipose and muscle, was undertaken before and after administration of mineralocorticoid receptor antagonist potassium canrenoate and glucocorticoid receptor antagonist mifepristone (RU486).

RESULTS

During placebo, systemic plasma cortisol and corticosterone concentrations increased promptly after canrenoate. Cortisol uptake was detected from adipose but not muscle following canrenoate + RU486. Probenecid significantly increased systemic cortisol concentrations, and tended to increase corticosterone and ACTH concentrations, after combined receptor antagonism but had no effects on net glucocorticoid balance in either adipose or muscle. Using quantitative PCR in brain bank tissue, ABCC1 expression was 5-fold higher in human pituitary than hypothalamus and hippocampus. ABCB1 was more highly expressed in hypothalamus compared to pituitary.

CONCLUSIONS

Although displacement of corticosterone and/or cortisol from receptors in adipose and skeletal muscle could not be measured with sufficient precision to detect effects of probenecid, ABCC1 inhibition induced a greater incremental activation of the hypothalamic-pituitary-adrenal axis after combined receptor blockade, consistent with ABCC1 exporting corticosterone from the pituitary and adding to the evidence that ABC transporters modulate tissue glucocorticoid sensitivity.

Testing the immunocompetence handicap hypothesis: Testosterone manipulation does not affect wound healing in male salamanders

In vertebrates, a bidirectional relationship exists between the immune system and the hypothalamic-pituitary-gonadal axis. In addition, sexual dimorphism in immunity has been documented in many vertebrates as well as some invertebrates, and males are generally less immunocompetent than their female counterparts. A possible explanation for this is described by the immunocompetence handicap hypothesis (ICHH), which proposes that elevated testosterone (T) levels direct resources towards the promotion of secondary sexual characteristics at a cost to immune function. To further test the ICHH, we examined the effects of T on cutaneous wound healing, an integrative measure of immunity, using male Allegheny Mountain dusky salamanders; a species that has sexually dimorphic courtship glands and testosterone-dependent mating behavior. We did this via two methods: surgical manipulation and transdermal delivery of T. In both experiments, elevated plasma T did not delay wound healing. Interestingly, intact animals healed more slowly than animals that had undergone prior invasive surgery, suggesting that the prior surgery had an immune-priming effect that enhanced healing of a second wound.

The effect of isoflurane anaesthesia and vasectomy on circulating corticosterone and ACTH in BALB/c mice

The use of blood corticosterone and faecal corticosterone metabolites as biomarkers of post-surgical stress and pain in laboratory animals has increased during the last decade. However, many aspects of their reliability in laboratory mice remain uninvestigated. This study investigated serum corticosterone and adrenocorticotropic hormone (ACTH) in mice subjected to isoflurane anaesthesia and vasectomy, and mice subjected to isoflurane anaesthesia without surgery. Serum levels of corticosterone and ACTH after pre-treatment with dexamethasone were analysed to provide further information about the stress hormone profiles. Vasectomy resulted in an increase in corticosterone for at least four hours after surgery with a peak 30min after the mice regained righting reflex. Mice subjected to isoflurane anaesthesia without surgery had the highest level of serum corticosterone 5min after regained righting reflex and the level returned to baseline levels four hours after the procedure. In vasectomised mice, treated with dexamethasone, high levels of corticosterone remained 30min after the procedure, whereas the anaesthetised mice, treated with dexamethasone, had significantly lower levels of corticosterone compared to anaesthetised mice not treated with dexamethasone. Thus, dexamethasone effectively inhibited the corticosterone response in the anaesthetised-only mice, but not in the mice subjected to surgery. In conclusion, both isoflurane anaesthesia and vasectomy during isoflurane anaesthesia resulted in an increase in serum glucocorticoids, but the negative feedback mechanism of newly operated mice, was altered. This may have consequences for the interpretation of glucocorticoids measurements as a biomarker of post-surgical stress in mice.

Measurements of serum free cortisol in critically ill patients

BACKGROUND

Because more than 90 percent of circulating cortisol in human serum is protein-bound, changes in the binding proteins can alter measured serum total cortisol concentrations without influencing free concentrations of this hormone. We investigated the effect of decreased amounts of cortisol-binding proteins on serum total and free cortisol concentrations during critical illness, when glucocorticoid secretion is maximally stimulated.

METHODS

Base-line serum total cortisol, cosyntropin-stimulated serum total cortisol, aldosterone, and free cortisol concentrations were measured in 66 critically ill patients and 33 healthy volunteers in groups that were similar with regard to sex and age. Of the 66 patients, 36 had hypoproteinemia (albumin concentration, 2.5 g per deciliter or less), and 30 had near-normal serum albumin concentrations (above 2.5 g per deciliter).

RESULTS

Base-line and cosyntropin-stimulated serum total cortisol concentrations were lower in the patients with hypoproteinemia than in those with near-normal serum albumin concentrations (P<0.001). However, the mean (+/-SD) base-line serum free cortisol concentrations were similar in the two groups of patients (5.1+/-4.1 and 5.2+/-3.5 microg per deciliter [140.7+/-113.1 and 143.5+/-96.6 nmol per liter]) and were several times higher than the values in controls (0.6+/-0.3 microg per deciliter [16.6+/-8.3 nmol per liter], P<0.001 for both comparisons). Cosyntropin-stimulated serum total cortisol concentrations were subnormal (18.5 microg per deciliter [510.4 nmol per liter] or less) in 14 of the patients, all of whom had hypoproteinemia. In all 66 patients, including these 14 who had hypoproteinemia, the base-line and cosyntropin-stimulated serum free cortisol concentrations were high-normal or elevated.

CONCLUSIONS

During critical illness, glucocorticoid secretion markedly increases, but the increase is not discernible when only the serum total cortisol concentration is measured. In this study, nearly 40 percent of critically ill patients with hypoproteinemia had subnormal serum total cortisol concentrations, even though their adrenal function was normal. Measuring serum free cortisol concentrations in critically ill patients with hypoproteinemia may help prevent the unnecessary use of glucocorticoid therapy.

Adrenocortical function: an indicator of severity of disease and survival in chronic critically ill patients

Plasma cortisol levels and modified Apache II (Apache IIm-stay) severity of disease scores were determined at weekly intervals in 159 patients who were treated for at least 7 days at the Critical Care Unit of our hospital. The mean (+/- SD) plasma cortisol level (0.60 +/- 0.28 mumol/l) was clearly elevated in these patients. The highest plasma cortisol levels were measured in patients treated with vasoactive drugs (0.76 +/- 0.39 mumol/l). Non-survivors (n = 36) had a significantly higher mean plasma cortisol level and Apache IIm-stay score than survivors (respectively 0.78 +/- 0.40 vs. 0.54 +/- 0.21 mumol/l; p less than 0.0003 and 12.6 +/- 4.8 vs. 7.3 +/- 4.1; p less than 0.0001). A significant correlation was found between the individual weekly plasma cortisol levels and the Apache IIm-stay scores (r = 0.41; p less than 0.0001), especially in the subgroup of patients, who never received glucocorticoids during their stay at the ICU (r = 0.51; p less than 0.0001). During the 14-month study period only two patients showed a clinical picture of adrenocortical insufficiency and a blunted response of cortisol to 0.25 mg synthetic ACTH(1-24). In conclusion, our data suggest that a high plasma cortisol level, like a high Apache IIm-stay score, indicates severity of disease and poor survival in critically ill patients. De novo adrenocortical insufficiency is rare and therefore routine screening of adrenocortical function is superfluous.

Adrenal function following coronary bypass surgery

Little is known about adrenocortical function after coronary bypass surgery in which moderate to deep hypothermia and cardiopulmonary bypass are used particularly with intraoperative steroid administration. Therefore, we performed a pilot study in which immediately preoperative and 18-hour postoperative serum cortisol levels were determined in eight patients who received 1.0 to 1.5 gm of methylprednisolone intravenously during surgery; postoperative serum cortisol (3 +/- 1 microgram%) levels were lower than preoperative levels (15 +/- 3 microgram%, p less than 0.05). To determine the possible cause of these striking findings, the effects of moderate to profound hypothermia and cardiopulmonary bypass upon adrenocortical functioning were investigated without the influence of intraoperative steroid administration. Serum cortisol and aldosterone levels and their response to adrenocorticotropic hormone (ACTH) (Cortrosyn) were determined before coronary bypass surgery and at various postoperative intervals in seven patients. Postoperative cortisol and aldosterone levels increased markedly over their preoperative values, reaching a maximum at 6 to 12 hours (cortisol 16 +/- 8 vs 63 +/- 23 micrograms%, p less than 0.05, aldosterone 15 +/- 5 vs 51 +/- 22 ng%, p less than 0.05). Adrenal response to ACTH was normal preoperatively, during rewarming from hypothermia, and 18 hours, and 7 days postoperatively. In summary, normal adrenal responsiveness occurs after coronary bypass surgery, in spite of hypothermic cardiopulmonary bypass and the effects of anesthesia, and a single dose of methylprednisolone during surgery is associated with markedly lower serum cortisol levels and prevents the usual adrenal stress response to bypass surgery for at least 18 hours postoperatively.

Prolonged disruption of plasma beta-endorphin dynamics following surgery

The purpose of the present study was to examine the effects of surgery on plasma beta-endorphin dynamics. Plasma beta-endorphin levels were measured by liquid chromatography/radioimmunoassay in seven patients undergoing elective surgery. Blood samples were obtained every 4 hr for two 24-hr periods: one beginning 48 hr before surgery and the other beginning 48 hr after surgery. Computer analysis of beta-endorphin levels as a function of clock time demonstrated a true circadian rhythm preoperatively with a mean of 28.0 +/- 5.9 pg/ml. In the postoperative period mean beta-endorphin levels were significantly elevated (85.6 +/- 20.7 pg/ml, P less than 0.005). Surgical procedures caused significant phase shifting in the grouped mean circadian rhythm of plasma beta-endorphin (mean = 2.4 hr). When the data was analyzed individually, plasma circadian rhythms were found to be totally abolished in the three patients with the longest operative times (mean = 3.8 hr) and significantly displaced in time in the remaining four patients. These prolonged alterations in plasma endogenous opioid peptide levels following surgery have not been previously reported, and should be considered in the management of the postsurgical patient.

[Hemodynamic and hormonal study of electronarcosis and neuroleptanalgesia. Clinical study in 17 surgical patients]

The blocking effect of electropharmaceutical anesthesia (EPA) and neuroleptanalgesia (NLA) on adrenergic and hormonal reactions to abdominal surgery were compared in 17 ASA class I to III randomized patients. This study was intended to define the indications for each of these techniques in patients with heart diseases. Each individual received the same anesthetic premedication and induction and was submitted to iterative identical measurements and biological dosages. Before and during surgery, both groups were catheterized with a Swan-Ganz and a radial catheter. Blood sampling for catecholamines, cortisol, glycemia, blood gases dosages were regularly drawn. Electrical stimulation was performed in the EPA group, and fentanyl injections were repeated in the NLA group patients only. The same doses of pancuronium and droperidol were given to every patient. A circulatory hyperkinesia and hyperadrenergia were observed during surgery in all of the subjects but, during EPA, the tachycardia, the cardiac index and the rate-pressure product were higher than during NLA. The body temperature increased towards normal in EPA, not in NLA. Adrenergic and hormonal levels were equal in both groups. The slow variations of all the important parameters demonstrate that the measured phenomenons have a long time-course what legitimates this kind of prolonged on-the-spot observation. The role of droperidol, pancuronium and fentanyl in the observed variations is discussed. The characteristic high hyperkinesia in EPA may be due partly to an inefficacious analgesia because of the fentanyl suppression after induction, partly to the preserved thermogenesis partly to a direct effect of the electrical stimulation on cerebral tissues.

Human corticosteroid binding globulin

The literature on corticosteroid binding globulin (transcortin) in the human is reviewed under the following headings: physicochemical properties, biosynthesis, measurement, and physiological, pharmacological and pathological variations with particular emphasis of the effects of pregnancy and oral contraceptives. Finally, the physiological implications of corticosteroid binding globulin are discussed.

Simultaneous radioimmunoassay for corticosterone and deoxycortisol in human serum: sex differences in the mean serum concentrations

A specific radioimmunoassay is described which allows the simultaneous determination of serum corticosterone and deoxycortisol. The method involves extraction with dichloromethane, purification by paper chromatography in a modified Bush-system and quantitation by radioimmunoassay. The normal serum concentration of both steroids were found to be dependent on sex and menstrual cycle. Mean concentrations (+/- S.D.) in males, females (follicular phase) and females (luteal phase) were 4210 +/- 2170 ng/1,2410 + 1480 ng/1 and 4390 +/- 2320 ng/1 for corticosterone and 499 +/- 273 ng/1, 207 +/- 152 ng/1 and 335 +/- 182 ng/1 for deoxycortisol. After adrenal stimulation by corticotropin itself or by insulin induced hypoglycemia, the serum concentrations of corticosterone became significantly higher than those of deoxycortisol. After oral administration of dexamethasone serum concentrations of both steroids were suppressed to levels below the limit of the normal range. One hour after oral metyrapone administration at midnight, serum corticosterone decreased, while serum deoxycortisol increased by a factor of about five. After eight hours serum concentrations of both steroids were increased considerably. Corticosterone attained levels slightly higher than the normal range and deoxycortisol rose to levels which were higher than the normal mean concentrations by a factor of about 500.

Cerebrospinal fluid and plasma free cortisol concentrations in depression

Cerebrospinal fluid (CSF) cortisol levels were examined in a total group of 65 patients. Those who were not depressed (ND), and those suffering from depressive neuroses (DN) had marginally elevated values. Patients with unipolar depression (UD) and bipolar depression (BD) had levels twice as high as the ND and DN patients. Psychotic UD and BD patients had the highest values, three to four times as high as the ND and DN subjects. A significant reduction of CSF cortisol levels was observed following treatment and recovery. Manic patients had moderately elevated CSF cortisol values. The CSF results were in good agreement with plasma total cortisol levels and with urinary free cortisol excretion. Age and sex effects were not responsible for the observed differences; similar results were found in patient subgroups studied in Australia and in the United States. Preliminary equilibrium dialysis data are presented for plasma and CSF cortisol binding. CSF cortisol was 20% bound and 80% free. Plasma free cortisol levels were in good agreement with CSF free cortisol values. Depressed patients have increased tissue and central nervous system (CNS) exposure to free, physiologically active glucocorticoids. The appearance of severe depressive symptoms which manifest a diurnal rhythm may be determined in part by excesssve CNS exposure to glucocorticoids.

Urinary free cortisol excretion in depression

Urinary free cortisol (UFC) excretion was determined in 60 depressed inpatients and in 35 psychiatric inpatients with other disorders. The depressed patients had high daily UFC values, while the other patients excreted normal amounts. Over 40% of the depressed patients had UFC excretions in the range seen in Cushing's disease, while only 6% of the other patients excreted such high amounts of cortisol. Age and sex differences did not account for the results. Among the depressed patients those with depressive neuroses excreted less than unipolar or bipolar depressives. Following treatment, more normal UFC excretion was found in depressed patients. The estimation of UFC and its clinical utility are discussed in detail. UFC determination is a simple and informative indicator of adrenal cortical activation and its application to psychoendocrine studies is recommended.

A rational approach to dosage and preparation of parenteral glucocorticoid substitution therapy during surgical procedures. A short review

A rational physiological schedule for parenteral glucocorticoid substitution therapy during surgical procedures is proposed based on the principle of imitating the normal hypothalamic-pituitary-adrenocortical response to surgery. The schedule includes the injection of 25 mg cortisol intravenously in all patients together with induction of anaesthesia. Following major surgery, 100 mg cortisol dissolved in saline or glucose is continuously infused intravenously every 24 hours until gastrointestinal function permits oral intake of usual glucocorticoid substitution therapy. In case continuous cortisol infusion is undesirable, 25 mg cortisol is injected intravenously every four hours. Following minor surgery, usual oral glucocorticoid therapy is started immediately after the operation. It is recommended to use water-soluble cortisol preparations and not cortisone acetate, which results in limited plasma cortisol levels.

The concentrations of total cortisol and corticosterone in mixed cord plasma

Cortisol and corticosterone were determined in mixed umbillical cord plasma of 43 healthy full-term newborns. The method consisted of a combined thin-layer chromatographic-fluorimetric procedure which proved to be specific and reliable. The mean concentration in cord plasma of cortisol was 10.6 plus or minus 4.9 mug/100 ml, of corticosterone 1.8 plus or minus 0.8 mug/100 ml. The mean ratio cortisol/corticosterone F/B was 6.3 plus or minus 2.5. Neither the duration nor the time of day of delivery appeared to influence the concentration of cortisol or corticosterone in umbilical cord plasma. Also, there was no significant difference between male and female infants. In 18 instances of a pathological course of gestation and/or delivery the mean cortisol level was 9.1 plus or minus /.7 mug/ml, the mean corticosterone level 2.2 plus or minus 9 mug/100ml. The mean F/B ratio was slightly but not significantly decreased (4.2 plus or minus 1.4 mug/100 mo; p larger than 0.05). It is speculated that the high corticosterone concentration in umbilical cord plasma reflects a defect in cortisol biosynthesis (17 chi-hydroxylase deficiency) in the newborn, compared with later life.