Twenty-four hour hormonal and metabolic profiles in uraemic patients before and during treatment with continuous ambulatory peritoneal dialysis

Cortisol excess in chronic kidney disease - A review of changes and impact on mortality

Chronic kidney disease (CKD) describes the long-term condition of impaired kidney function from any cause. CKD is common and associated with a wide array of complications including higher mortality, cardiovascular disease, hypertension, insulin resistance, dyslipidemia, sarcopenia, osteoporosis, aberrant immune function, cognitive impairment, mood disturbances and poor sleep quality. Glucocorticoids are endogenous pleiotropic steroid hormones and their excess produces a pattern of morbidity that possesses considerable overlap with CKD. Circulating levels of cortisol, the major active glucocorticoid in humans, are determined by a complex interplay between several processes. The hypothalamic-pituitary-adrenal axis (HPA) regulates cortisol synthesis and release, 11β-hydroxysteroid dehydrogenase enzymes mediate metabolic interconversion between active and inactive forms, and clearance from the circulation depends on irreversible metabolic inactivation in the liver followed by urinary excretion. Chronic stress, inflammatory states and other aspects of CKD can disturb these processes, enhancing cortisol secretion via the HPA axis and inducing tissue-resident amplification of glucocorticoid signals. Progressive renal impairment can further impact on cortisol metabolism and urinary clearance of cortisol metabolites. Consequently, significant interest exists to precisely understand the dysregulation of cortisol in CKD and its significance for adverse clinical outcomes. In this review, we summarize the latest literature on alterations in endogenous glucocorticoid regulation in adults with CKD and evaluate the available evidence on cortisol as a mechanistic driver of excess mortality and morbidity. The emerging picture is one of subclinical hypercortisolism with blunted diurnal decline of cortisol levels, impaired negative feedback regulation and reduced cortisol clearance. An association between cortisol and adjusted all-cause mortality has been reported in observational studies for patients with end-stage renal failure, but further research is required to assess links between cortisol and clinical outcomes in CKD. We propose recommendations for future research, including therapeutic strategies that aim to reduce complications of CKD by correcting or reversing dysregulation of cortisol.

Growth Hormone and Malnutrition in Dialysis Patients

Objective

To review the normal function of the growth hormone (GH) insulin-like growth factor (IGF) axis, how it is altered in end-stage renal failure, how this may contribute to malnutrition in dialysis patients, and how therapy with recombinant human growth hormone (rHuGH) and recombinant human IGF-I (rHuIGF-1)might be used to treat malnutrition in these patients.

Data Sources

Studies in the literature dealing with the GH-IGF endocrine axis and its role in uremic malnutrition.

Study Selection

Eight studies in which uremic adults were treated with either rHuGH or rHuIGF-I.

Data Extraction

Data were abstracted from all of these studies.

Results

The review shows that there are marked abnormalities of the GH-IGF axis in uremic patients and that these lead to a state of GH resistance, which can be overcome by pharmacological doses of rHuGH. A small number of clinical studies in uremic adults suggests that both rHuGH and rHuIGF-I have dramatic beneficial effects on nutritional status in these patients.

Conclusions

rHuGH and rHuIGF-I have both been shown to have a beneficial effect on nutritional status in shortterm studies on small numbers of patients. Further studies need to be done for longer periods in larger groups of patients. Areas for additional research are suggested.

Growth Hormone and Malnutrition in Dialysis Patients

Objective

To review the normal function of the growth hormone (GH) insulin-like growth factor (IGF) axis, how it is altered in end-stage renal failure, how this may contribute to malnutrition in dialysis patients, and how therapy with recombinant human growth hormone (rHuGH) and recombinant human IGF-I (rHuIGF-1)might be used to treat malnutrition in these patients.

Data Sources

Studies in the literature dealing with the GH-IGF endocrine axis and its role in uremic malnutrition.

Study Selection

Eight studies in which uremic adults were treated with either rHuGH or rHuIGF-I.

Data Extraction

Data were abstracted from all of these studies.

Results

The review shows that there are marked abnormalities of the GH-IGF axis in uremic patients and that these lead to a state of GH resistance, which can be overcome by pharmacological doses of rHuGH. A small number of clinical studies in uremic adults suggests that both rHuGH and rHuIGF-I have dramatic beneficial effects on nutritional status in these patients.

Conclusions

rHuGH and rHuIGF-I have both been shown to have a beneficial effect on nutritional status in shortterm studies on small numbers of patients. Further studies need to be done for longer periods in larger groups of patients. Areas for additional research are suggested.

Clinical and biochemical factors to predict biochemical adrenal insufficiency in hospitalized patients with indeterminate cortisol levels: a retrospective study

BACKGROUND

Adrenal insufficiency (AI) in hospitalized patients is a fatal condition if left undiagnosed. Most patients may require an adrenocorticotropic hormone (ACTH) stimulation test to facilitate AI diagnosis. We aim to identify simple biochemical and clinical factors and derive a predictive model to help identify hospitalized patients with biochemical AI who have indeterminate 0800 h serum cortisol levels.

METHODS

A seven-year retrospective study was performed in a tertiary care medical center. We identified 128 inpatients who had undergone low-dose or high-dose ACTH stimulation tests. The association between biochemical AI and other factors was evaluated using a logistic regression model clustering by ACTH dose. Stepwise regression analysis was used to demonstrate the predictive model. Diagnostic performance was evaluated using ROC analysis.

RESULTS

Of the 128 patients, 28.1% had biochemical AI. The factors associated with biochemical AI were serum random cortisol < 10 μg/dL (OR = 8.69, p < 0.001), cholesterol < 150 mg/dL (OR = 2.64, p = 0.003), sodium < 140 mmol/L (OR = 1.73, p = 0.004)). Among clinical factors, cirrhosis (OR = 9.05, p < 0.001), Cushingoid appearance in those with exogenous steroid use (OR = 8.56, p < 0.001), and chronic kidney disease (OR = 2.21, p < 0.001) were significantly linked to biochemical AI. The AUC-ROC of the final model incorporating all factors was 83%.

CONCLUSIONS

These easy-to-perform biochemical tests and easy-to-assess clinical factors could help predict biochemical AI in hospitalized patients with high accuracy. The physician should therefore have a high index of suspicion to perform dynamic tests for AI diagnosis in those who meet the proposed model criteria.

Blood Oxygenation Level-Dependent Functional MRI of Early Evidences of Brain Plasticity after Hemodialysis Session by Helixone Membrane of Patients with Indices of Adrenal Deficiency

BACKGROUND

Various alterations of hypothalamic-pituitary-adrenal axis function have been described in patients with chronic renal failure. Nevertheless, controversial evidences were stated about the association between adrenal function deficiency (AD) and hemodialysis (HD).

PURPOSE

The goal of this paper was to estimate indirect indices of the adrenal gland dysfunction which is potentially influenced by oxidative stress (OS) that still generates brain plasticity and reorganization of the functional control.

METHODS

Two male patients undergoing HD by the synthetic Helixone membrane for more than 6 months at the HD Center of the University Hospital of Fez, Fez, Morocco, were recruited. They underwent identical assessment immediately before and after the full HD session; this consisted of a blood ionogram revealing rates of sodium and calcium, and brain blood oxygenation level-dependent functional MRI (BOLD-fMRI) using a motor paradigm in block design.

RESULTS

The blood ionogram revealed hypercalcemia and hyponatremia in both patients. Both biological assessment and BOLD-fMRI study results revealed a high level of OS that induced activation of a significantly large brain volume area suggesting the occurrence of possible brain plasticity and functional control reorganization induced by free radicals and enhanced by AD.

CONCLUSION

The occurrence of brain plasticity and functional control reorganization was demonstrated in both patients studied who were undergoing HD by BOLD-fMRI with a notable sensitivity; this plasticity is induced by elevated OS occasioned by HD technique itself and probably amplified by AD. Similar results were found in a previous study performed on the same patients undergoing HD by a polysulfone membrane.

Indices of adrenal deficiency involved in brain plasticity and functional control reorganization in hemodialysis patients with polysulfone membrane: BOLD-fMRI study

This work purpose was to estimate the implication of suspected adrenal function deficiencies, which was influenced by oxidative stress (OS) that are generating brain plasticity, and reorganization of the functional control. This phenomenon was revealed in two-hemodialysis patients described in this paper. Blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) revealed a significant activation of the motor cortex. Hemodialysis seems to originate an inflammatory state of the cerebral tissue reflected by increased OS, while expected to decrease since hemodialysis eliminates free radicals responsible for OS. Considering adrenal function deficiencies, sensitivity to OS and assessed hyponatremia and hypercalcemia, adrenal function deficiencies is strongly suspected in both patients. This probably contributes to amplify brain plasticity and a reorganization of functional control after hemodialysis that is compared to earlier reported studies. Brain plasticity and functional control reorganization was revealed by BOLD-fMRI with a remarkable sensitivity. Brain plastic changes are originated by elevated OS associating indices of adrenal function deficiencies. These results raise important issues about adrenal functional deficiencies impact on brain plasticity in chronic hemodialysis-patients. This motivates more global studies of plasticity induced factors in this category of patients including adrenal functional deficiencies and OS.

Acid-base balance in peritoneal dialysis patients: a Stewart-Fencl analysis

BACKGROUND

Evaluation of acid-base disorders using the Stewart-Fencl principle is based on assessment of independent factors: strong ion difference (SID) and the total concentration of non-volatile weak acids (Atot). This approach allows for a more detailed evaluation of the cause of acid-base imbalance than the conventional bicarbonate-centered approach based on the Henderson-Hasselbalch principle, which is a necessary yet insufficient condition to describe the state of the system. The aim of our study was to assess acid-base disorders in peritoneal dialysis (PD) patients using both of these principles.

METHODS

A total of 17 patients with chronic renal failure (10 men), aged 60.7 (22-84) years, treated by PD for 25.7 (1-147) months were examined. A control group included 17 healthy volunteers (HV) (8 males), with a mean age of 42.7 (22-77) years and normal renal function. Patients were treated with a solution containing bicarbonate (25 mmol/L) and lactate (15 mmol/L) as buffers; eleven of them used, during the nighttime dwell, a solution with icodextrin buffered by lactate at a concentration of 40 mmol/L. The following equations were employed for calculations of acid-base parameters according to the Stewart-Fencl principle. The first is SID = [Na+] + [K+] + 2[Ca(2+)] + 2[Mg(2+)] - [Cl-] - [UA-], where SID is the strong ion difference and [UA-] is the concentration of undetermined anions. For practical calculation of SID, the second equation, SID = [HCO3-] + [Alb-] + [Pi-], was used, where [Alb-] and [Pi-] are the charges carried by albumin and phosphates. The third is Atot, the total concentration of weak non-volatile acids, albumin [Alb] and phosphates [Pi].

RESULTS

The capillary blood pH in PD group was 7.41 (7.27-7.48), [HCO3-] levels 23.7 (17.6-29.5) mmol/L, SID 36.3 (29.5-41.3) mmol/L, sodium-chloride difference 39.0 (31.0-44.0) mmol/L, [Pi] 1.60 (0.83-2.54) mmol/L, and [Alb] 39.7 (28.8-43.4) g/L (median, min-max). Bicarbonate in blood correlated positively with SID (Rho = 0.823; p < 0.001), with the sodium-chloride difference (Rho = 0.649; p < 0.01) and pH (Rho = 0.754; p < 0.001), and negatively with residual renal function (Rho = -0.517; p < 0.05). Moreover, the sodium-chloride difference was also found to correlate with SID (Rho = 0.653; p < 0.01). While the groups of PD and HV patients did not differ in median bicarbonate levels, significantly lower median value of SID were observed in PD patients, 36.3 vs. 39.3 mmol/L (p < 0.01); additionally, PD patients were shown to have significantly lower mean value of serum sodium levels, 138 vs. 141 mmol/L (p < 0.01), and serum chlorides levels, 100 vs. 104 mmol/L (p < 0.001). Despite the higher [UA-] levels in PD patients, 9.1 vs. 5.4 mmol/L (p < 0.001), this parameter was not found to correlate with bicarbonate levels.

CONCLUSIONS

The results suggest that the decreased bicarbonate in PD patients results from a combination of decreased sodium-chloride difference and mildly increased unmeasured anions.

Insulin resistance in diabetic nephropathy--cause or consequence?

Insulin resistance (IR) is associated with multiple risk factors for cardiovascular disease. Many studies have shown that IR is present in chronic renal failure (CRF), and recent evidence suggests that IR can also occur in the early stages of renal disease. Patients with diabetic nephropathy (DN) have an increase in cardiovascular mortality, and since IR may be a contributing factor, this emphasizes the importance of a detailed understanding of the mechanisms linking IR and renal dysfunction at different stages of DN. IR can be detected early on in DN, e.g. at the stage of microalbuminuria (MA) and this could indicate a common genetic trait for IR and DN. As DN progresses further, IR is aggravated and it may, in addition to other factors, possibly accelerate the decline in renal function toward end-stage renal disease (ESRD). Several potentially modifiable mechanisms including circulating hormones, neuroendocrine pathways and chronic inflammation, are said to contribute to the worsening of IR. In ESRD, uremic toxins are of major importance. In this review article, we address the association between different stages of DN and IR and attempt to summarize major findings on potential mechanisms linking DN and IR. We conclude that IR is a consequence, and potentially also a cause of DN. In addition, there are probably genetic and environmental background factors that predispose to both IR and DN.

Growth hormone, IGF-I and its binding proteins (IGFBP-1 and -3) in adult uraemic patients undergoing peritoneal dialysis and haemodialysis

OBJECTIVE

The GH/IGF axis is altered in chronic renal failure (CRF). CRF patients usually show normal or high serum concentrations of GH and IGF-I, whereas all IGF binding proteins (IGFBP-1 to -6), except IGFBP-5, considerably increase with declining renal function. The aims of the present study were to quantify serum concentrations of GH, IGF-I, IGFBP-1 and IGFBP-3 in a group of patients with CRF, and determine whether there were differences according to the type of dialysis, that is, peritoneal dialysis (PD) and haemodialysis (HD).

DESIGN

A cross-sectional study in the setting of a dialysis unit of a general hospital.

PATIENTS AND MEASUREMENTS

We studied 108 dialysis patients treated by PD (n = 54, 32 males and 22 females, mean age 61.0 +/- 1.4 years) or HD (n = 54, 31 males and 23 females, age 62.6 +/- 1.5 years). A group of 42 healthy subjects of similar age, sex and body mass index (BMI) served as the control group. Baseline serum concentrations of GH, insulin, IGF-I, IGFBP-1 and IGFBP-3 were measured in all patients and control subjects.

RESULTS

Fasting serum concentrations of IGF-I and its binding proteins (IGFBP-1 and IGFBP-3) were significantly higher in dialysis patients than in subjects with normal renal function. IGF-I (248.9 +/- 23.4 vs. 205.5 +/- 15.5 micro g/l, NS), IGFBP-3 (5.6 +/- 0.4 vs. 5.5 +/- 0.2 mg/l, NS) and IGFBP-1 (36.1 +/- 5.9 vs. 44.1 +/- 6.5 micro g/l, NS) concentrations were similar in both groups of dialysis (PD vs. HD) patients. However, GH (2.3 +/- 0.3 vs. 1.1 +/- 0.1 micro g/l, P < 0.001) and insulin (40.4 +/- 4.5 vs. 30.1 +/- 3.1 micro U/ml, P < 0.05) levels were significantly higher in the PD group than in the HD group. Both groups of dialysis patients showed significantly higher levels of insulin than healthy subjects (14.7 +/- 1.9 micro U/ml, P < 0.0001 and P < 0.01 for PD and HD, respectively). In both groups of dialysis patients, IGF-I correlated inversely with IGFBP-1 (PD group r = -0.46, P = 0.0006; HD group r = -0.57, P = 0.0001) and directly with IGFBP-3 (PD group r = 0.44, P = 0.001; HD group r = 0.73, P = 0.001). No correlation between insulin and IGFBP-1 was found in any of the groups studied.

CONCLUSIONS

These findings demonstrate that adult dialysis patients have elevated IGF-I, IGFBP-1 and IGFBP-3 serum concentrations compared with subjects with normal renal function. Only GH and insulin show statistically significant differences in relation to type of dialysis. Finally, the negative correlation between IGF-I and IGFBP-1 and the positive correlation between IGF-I and IGFBP-3 are maintained in both groups of adult dialysis patients.

The midnight-to-morning urinary cortisol increment method is not reliable for the assessment of hypothalamic-pituitary-adrenal insufficiency in patients with end-stage kidney disease

A previous study reported that the midnight-to-morning urinary cortisol increment method could be used to reliably assess the insufficiency of the hypothalamic-pituitary-adrenal (HPA) axis. The principal aim of the present study is to verify whether the midnight-to-morning urinary cortisol increment is a reliable method for the assessment of the HPA axis in patients with various degrees of impaired kidney function. Fifty-six clinically stable patients with chronic kidney disease (CKD) and 14 healthy subjects were enrolled in the present study. Patients with CKD were divided on the basis of glomerular filtration rate (GFR) into the following arbitrary groups: mild (GFR: 60-89 ml/min/1.73 m2, no.=15), moderate (GFR: 30-59 ml/min/1.73 m2, no.=12) and severe kidney insufficiency (GFR: 15-29 ml/min/1.73 m2, no.=13), and hemodialysis patients. Plasma cortisol and ACTH levels were measured. The HPA axis was assessed by short Synacthen test and overnight dexamethasone suppression test. Double voided urine samples were collected at midnight and waking in the patients and the controls. Urinary free cortisol (UFC) and creatinine levels were measured and the UFC/creatinine ratio (Cort/Cr) was calculated. Then, the Cort/Cr increment was calculated as the morning Cort/Cr minus the midnight Cort/Cr. Baseline plasma cortisol levels were not significantly different between two groups. However, we found that CKD patients had significantly greater plasma ACTH levels than controls. The patients with CKD had also significantly lower morning UFC levels than controls and there was a progressive fall in morning UFC levels with decreasing GFR. The assessment of the HPA axis in patients with GFR lower than 29 ml/min was hampered by falsely abnormal responses to the midnight-to-morning urinary cortisol increment method. Plasma cortisol responded normally to exogenously administered ACTH, while plasma cortisol was suppressed by overnight dexamethasone administration in all patients with CKD. In conclusion, this method is not a reliable test for assessment of the HPA insufficiency in patients with GFR lower than 29 ml/min.

Effects of recombinant human growth hormone in catabolic adults with chronic renal failure

Growth hormone (GH) has been used for the treatment of catabolism in a few pilot studies and in two placebo-controlled studies of 6 months duration. Treatment with GH in doses of 2-4 IU/m2/day (0.67-1.33 mg/m2/day) resulted in clear anabolic effects and a significant change in body composition. Lean body mass increased by more than 3 kg within 6 months, whereas fat mass was decreased by the same amount, resulting in a constant total body weight. As there were no major side-effects, controlled long-term studies are justified.

1% amino acid peritoneal dialysate: single-cycle study in diabetic patients with end-stage renal disease

Uremia is associated with multiple abnormalities of carbohydrate and protein metabolism, which are partially corrected by continuous ambulatory peritoneal dialysis with dextrose-based solutions. The hormonal and metabolic effects of amino acid (AA)-based peritoneal dialysis have been studied in nondiabetic uremic patients. Such solutions may be particularly suitable for diabetic patients with end-stage renal disease provided the safety and efficacy of such solutions can be established. We have studied and compared the metabolic and hormonal responses to a single-cycle exchange of dextrose versus a 1% AA-based continuous ambulatory peritoneal dialysis solution in six diabetic patients with end-stage renal disease. In the fasting state and under similar free insulin concentrations, use of the AA solution led to a higher mean glucose concentration (109 +/- 16 mg/dL with dextrose solution v 128 +/- 25 mg/dL with AA solution, P < 0.05). Levels of alanine, lactate, pyruvate, glycerol, non-esterified fatty acids, and triglycerides were similar with the use of either solution. Use of the AA-based solution led to increases in the mean values of the branched chain AAs for the period of the study (valine 131 +/- 10 mumol/L with dextrose solution v 331 +/- 40 mumol/L with AA solution, P < 0.01; leucine 72 +/- 7 mumol/L with dextrose solution v 129 +/- 11 mumol/L with AA solution, P < 0.01; isoleucine 48 +/- 5 mumol/L with dextrose solution v 103 +/- 11 mumol/L with AA solution, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adipocyte insulin binding and insulin action in chronic renal failure before and during continuous ambulatory peritoneal dialysis

In order to investigate the cellular mechanisms of the insulin resistance displayed by subjects with chronic renal failure, adipocyte insulin receptor status and in vitro insulin sensitivity were studied. Adipocytes from uremic subjects displayed normal maximum specific insulin binding (2.55 +/- 0.23 v 2.57 +/- 0.09% per 10 cm2 cell membrane, although half-maximum binding was observed at 91 +/- 8 (uremic) and 139 +/- 11 (control) pmol/L (P less than 0.005). In six subjects restudied after three months of continuous ambulatory peritoneal dialysis, maximum specific insulin binding fell as a consequence of changes in both receptor affinity and number (2.87 +/- 0.20 v 2.05 +/- 0.17% per 10 cm2 cell membrane, P less than 0.01). Basal and maximal rates of lipogenesis were similar in the uremic and control groups, and half-maximal stimulation occurred at 13.5 +/- 4.4 and 21.4 +/- 3.0 pmol/L, respectively (NS). During continuous ambulatory peritoneal dialysis, adipocyte insulin sensitivity did not change significantly as assessed by stimulation of lipogenesis or glucose uptake (half-maximal stimulation at 12.0 +/- 4.0 v 26.4 +/- 11.0 and 23.1 +/- 7.1 v 29.0 +/- 7.5 pmol/L, before and during dialysis, respectively). These data suggest either that adipose tissue and muscle display differential insulin sensitivities in chronic renal failure or that other factors such as circulating inhibitors of insulin action are not detected by in vitro assays.