Sepsis, glucose intolerance, and protein malnutrition: a metabolic paradox

Advances in the detection and management of cystic fibrosis related diabetes

PURPOSE OF REVIEW

This review will outline the screening, diagnosis and management of cystic fibrosis related diabetes (CFRD). It will also discuss advances in the detection of early glucose abnormalities, their clinical significance and the emerging role for early insulin therapy.

RECENT FINDINGS

Before the onset of diabetes (as currently defined), patients with cystic fibrosis (CF) display glucose abnormalities, detectable either by 30-minutely sampled oral glucose tolerance testing (OGTT), or by continuous ambulatory interstitial glucose monitoring (CGM). These early glucose abnormalities are associated with the presence of glucose in airway fluid, potentially promoting the growth of airway pathogens and contributing to the progression of respiratory disease. Progressive insulin deficiency underlies these glucose abnormalities, and insulin deficiency also causes catabolism. Pilot studies of once-daily insulin therapy in the early stages of insulin deficiency show improved lung function and weight gain (important predictors of survival in CF).

SUMMARY

Early stages of insulin deficiency may be contributing to catabolism and deteriorating lung function in CF. It is plausible that early insulin therapy may prevent this deterioration, a view supported by pilot studies. Randomized controlled trials of early insulin therapy will now determine whether insulin therapy should be commenced earlier than current practice in CF.

Systemic and splanchnic metabolic response to exogenous human growth hormone

BACKGROUND

Evidence exists indicating that growth hormone (GH) resistance in some disease states such as hypercatabolic conditions may limit the metabolic benefit associated with recombinant human growth hormone (rhGH) administration. It was the purpose of this study to compare the systemic and splanchnic effects of rhGH in patients with sepsis exhibiting systemic inflammatory response syndrome (SIRS) with the response observed in normal volunteers. Because insulin-like growth factor I (IGF-I) is believed to be the dominant factor responsible for the anabolic effects of rhGH, particular attention was given to this secondary effector.

METHODS

The systemic and splanchnic effects of rhGH (0.15 mg/kg/day) were studied in normal volunteers (n = 5), critically ill patients with sepsis exhibiting SIRS (n = 6), and patients with sepsis exhibiting SIRS while receiving total parenteral nutrition (n = 6). Basal and end study IGF-I, urinary urea excretion, hepatic blood flow, hepatic venous oxygen content, and splanchnic oxygen exchange were measured after a 48-hour course of rhGH.

RESULTS

Fasting basal IGF-I concentrations were reduced by 75% to 83% in patients with sepsis/SIRS relative to normal control subjects. After 48 hours of rhGH, peak IGF-I concentrations were 74% and 76% lower in patients in the Sepsis/SIRS and Sepsis/SIRS + Nutrition groups, respectively, compared with normal control subjects. Despite the attenuated IGF-I rise in patients, urea excretion declined by a similar magnitude in all three groups. Hepatic blood flow remained unaffected, but rhGH administration increased splanchnic oxygen consumption in all groups (control, +57%*; Sepsis/SIRS, +13%; Sepsis/SIRS + Nutr +42%*; *p < 0.05 relative to corresponding basal) resulting in a decline of basal to end therapy hepatic venous oxygen saturation (control, 67 +/- 4% to 62 +/- 11%; Sepsis/SIRS, 51% +/- 14% to 43% +/- 14%*; Sepsis/SIRS + Nutr, 62% +/- 11% to 55% +/- 16%; *p < 0.05 relative to corresponding control value), suggesting that rhGH may induce centrilobular hepatic hypoxia, which may contribute to the diminished IGF-I response.

CONCLUSIONS

Although critically ill patients exhibit an IGF-I increase in response to exogenous rhGH, the rise is markedly attenuated compared with healthy volunteers, indicating the presence of GH resistance. Unexpectedly, the changes in the anabolic hormone IGF-I did not appear to be related to the reduction in urea excretion. This may provide some additional evidence for IGF-I resistance. Finally, rhGH is associated with an augmented splanchnic oxygen consumption but no corresponding increase in regional blood flow. As a result, regional tissue hypoxia may arise and contribute to the impaired or suboptimal IGF-I response pattern.

Elevated venous glutamate levels in (pre)catabolic conditions result at least partly from a decreased glutamate transport activity

Abnormally high postabsorptive venous plasma glutamate levels have been reported for several diseases that are associated with a loss of body cell mass including cancer, human/simian immunodeficiency virus infection, and amyotrophic lateral sclerosis. Studies on exchange rates in well-nourished cancer patients now show that high venous plasma glutamate levels may serve as a bona fide indicator for a decreased uptake of glutamate by the peripheral muscle tissue in the postabsorptive period and may be indicative for a precachectic state. High glutamate levels are also moderately correlated with a decreased uptake of glucose and ketone bodies. Relatively high venous glutamate levels have also been found in non-insulin-dependent diabetes mellitus and to some extent also in the cubital vein of normal elderly subjects, i.e., in conditions commonly associated with a decreased glucose tolerance and progressive loss of body cell mass.

Postoperative complications and survival after pancreatoduodenectomy in patients aged over 70 years

An analysis of postoperative complications and survival was conducted in 31 patients undergoing pancreatoduodenectomy (PD) for carcinoma of the pancreas or periampullary carcinoma. Of them, 11 were over 70 years of age and 20 were under 70. Anastomotic leakage was the most common complication after PD. Definite pancreatic leakage was found in one patient in the over 70 group, and one case each of pancreatic, biliary, and gastric leakage were found in the under 70 group. All complications were treated conservatively without any further operative intervention. The overall morbidity rate was 41.9% (13/31), being 45.5% (5/11) in the over 70 group and 40.0% (8/20) in the under 70 group, and no operative deaths occurred within 30 days after surgery. The cumulative survival rate of the patients aged over 70 years with carcinoma of the pancreas or periampullary carcinoma did not differ significantly from the rate of those under 70. It was thus concluded that PD achieves an adequate prognosis and survival in patients over 70 years of age.

Growth hormone improves muscle protein metabolism and whole body nitrogen economy in man during a hyponitrogenous diet

Healthy male volunteers (n = 12) were given a normocaloric hyponitrogenous diet for a conditioning period of 7 days. Thereafter they were blindly randomized to receive daily injections of methionyl recombinant human growth hormone (met-hGH) 0.06 IU/kg or saline during a second week of hyponitrogenous nutrition. The met-hGH group showed a lower urinary urea excretion and a lower serum concentration of urea as compared with the control group. In skeletal muscle, the polyribosome concentration, indicative of muscle protein synthesis, as well as the concentrations of glutamine, alanine, aspartate, serine, and threonine, decreased in the control group, whereas no such changes were seen in the met-hGH-treated group. Since provision of met-hGH prevented protein catabolism in muscle and improved whole body nitrogen economy, investigations of the possible beneficial effects of met-hGH to prevent skeletal muscle vast after surgical trauma are advocated.

Effect of administered human growth hormone on protein metabolism in septic rats

The effect of administered human growth hormone (hGH) on protein metabolism in septic rats was investigated. Fifty-three male Wistar rates with SVC cannulation were divided into four groups. Group I (n = 10) underwent sham-operation. Sepsis was induced by cecal ligation in group II (n = 19), group III (n = 10), and group IV (n = 14). Isocaloric, isonitrogenous glucose/amino acids were infused for 4 days. hGH was administered in group III (100 mU/day) and group IV (200 mU/day) every day. Cumulative nitrogen balance (mg/kg) in group IV was significantly higher than in group II (p less than 0.01): group I, 1264 +/- 355; group II, 117 +/- 693; group III, 92 +/- 735; group IV, 1001 +/- 279. Cumulative urinary excretion of 3-methylhistidine (3-MH, mg/kg) did not differ between group II and group IV: group I, 6.2 +/- 0.9; group II, 12.0 +/- 2.2; group III, 13.4 +/- 2.9; group IV, 10.5 +/- 2.3. Serum albumin level in group IV (1.8 +/- 0.2 g/dl) was significantly higher than in group II (1.5 +/- 0.2 g/dl) (p less than 0.01). Blood urea nitrogen level in group IV (12.6 +/- 2.3 mg/dl) was significantly lower than in group II (18.8 +/- 7.4 mg/dl) (p less than 0.05). Although serum levels of glucose, insulin, triglyceride, and phospholipid were higher in sepsis groups than in sham-operated group, those levels did not differ among sepsis groups. Administration of hGH, 200 mU/day, resulted in marked nitrogen retention and had little effect on 3-MH excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Endocrine mediators of metabolism associated with injury and sepsis

We have studied the endocrine characteristics of 13 seriously ill patients with the use of a provocative intravenous glucose bolus. Notable in this stressed patient population was that no major interpatient differences in response to glucose were found for insulin, glucagon, cortisol, or epinephrine. However, following glucose challenge half of this group (7/13) exhibited a prominent "paradoxical" mean human growth hormone (hGH) elevation (26.4 +/- 9.3 microU/ml) whereas the others (6/13) exhibited only a minor increase (7.8 +/- 2.9 microU/ml). In addition, norepinephrine levels were significantly higher in the latter group suggesting that the adrenergic nervous system plays a major role in regulating hGH in stress.

Altered immunologic function and nitrogen metabolism associated with depression of plasma growth hormone

The specific role of endogenous growth hormone in regulating nitrogen metabolism during surgical stress and infection remains unclear. We have studied splanchnic amino acid uptake and plasma concentrations in patient groups exhibiting growth hormone hypersecretion or relative growth hormone depression in response to stress. Splanchnic amino acid uptake was similar in both groups although plasma levels were significantly higher in the presence of depressed growth hormone production suggesting increased net peripheral proteolysis. In association with this latter observation. T lymphocyte subset analysis revealed a greater incidence of depressed helper to suppressor cell ratios in the presence of depressed growth hormone suggesting a greater impairment of cellular immunity.

Circadian growth hormone and prolactin blood concentration during a self-limited viral infection and artificial hyperthermia in man

Growth hormone and prolactin blood concentrations were measured in five human volunteers over 28-hour periods including 24 hourly samples (0800 to 0800 hours) followed by an oral glucose tolerance test (0800 to 1100 hours) both preexposure and during the peak febrile phase of a self-limited viral infection, Sandfly fever. Several months after recovery, three of the subjects were studied for 24-hour periods while they sat in a tub of water at 41 degrees C for 2 hours from 1300 to 1500 hours. During all studies, mealtimes (0800 hours, 1130 hours, 1630 hours) and dark phase (2300 to 700 hours) were fixed. Growth-hormone concentrations were strikingly elevated throughout the 24-hour study done during the febrile period of Sandfly fever infection (P less than .01) except for the period of normal nocturnal release when they were not significantly different from the baseline study. No additional nocturnal surge was noted the already elevated growth-hormone values during the viral-induced fever. Growth-hormone values tended to decline slowly during the night but increased considerably during the glucose-tolerance test the following morning. These changes were similar to responses previously reported in patients with cases of malnutrition. A clear-cut increase in growth-hormone concentrations (P less than .001) was also seen during a brief 2-hour period of artificial hyperthermia, suggesting that elevated body temperature alone may explain part of the increase in growth-hormone values seen during the fever of infection. A nocturnal surge of growth hormone was still seen in the artificial hyperthermia study, albeit somewhat delayed.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum albumin levels in cancer patients receiving total parenteral nutrition

Serum albumin concentration is commonly used as an index of nutritional status and as an indicator of nutritional response in hospitalized patients receiving total parenteral nutrition (TPN). One hundred thirty-nine cancer patients receiving TPN for at least two weeks were studied. Albumin intake, serum albumin, fluid balance, and weight change was monitored from 14 to 100 days of TPN. Patients were classified into three groups: A) patients receiving no exogenous albumin; B) patients receiving less than 25 grams of exogenous albumin; and C) patients receiving at least 25 grams of exogenous albumin during their course of TPN. Linear regression analysis of serum albumin levels vs. time on TPN showed a minimal positive correlation for patients in groups B and C (r = 0.154 and r = 0.183, respectively). Further analysis showed a significant elevation of serum albumin levels only in patients in group C (p less than or equal to 0.05). Contingency table analysis showed statistically significant increase in the incidence of sepsis in patients treated with exogenous albumin (X2 = 10.50, df = 2, p less than 0.01). There was no relationship between the change in serum albumin concentrations and the number of patient deaths. In addition, no relationship between tumor burden and subsequent response of serum albumin levels were identified. Serum albumin levels do not increase in cancer patients receiving TPN, unless exogenous albumin is given. Serum albumin appears to be a poor index of nutritional response in cancer patients receiving TPN.

The effect of sepsis on the oxidation of carbohydrate and fat

Oxidative metabolism has been studied by indirect calorimetry in 27 patients with sepsis and in 7 non-septic patients while they were all receiving total parenteral nutrition. Glucose oxidation was reduced in the septic patients and fat oxidation continued despite the infusion of an excess of glucose. The extent of these changes depended on the severity of the septic state as measured by the scoring system described in the preceding paper. The mechanism of these changes is not known. They were not related to an elevation of the plasma nonesterified fatty acid concentration. Alterations must have occurred in the way fat was taken up and metabolized by the cells. Here insulin resistance and the highly significant positive relationship found between the plasma cortisol concentration and the sepsis score might be important.

Hormonal changes and their influence on metabolism and nutrition in the critically ill

This is a brief review of the observed hormonal alterations following trauma and sepsis. The major changes noted in the metabolic status of the stressed patient have been characterized by deranged carbohydrate metabolism, altered metabolic rate as measured by oxygen consumption and increased ureagenesis. Each of these phenomena are regulated to a large extent by the specific hormonal profile of the patient. Failure of insulin and growth hormone production have been associated with glucose intolerance, excessive urinary nitrogen loss and a fatal outcome. Glucagon, cortisol and catecholamines exhibit sustained elevation and have been associated with increased metabolic rate and excessive ureagenesis. These changes are usually self limited following trauma but will persist if the patient enters a septic phase. The use of specific nutritional support, namely hypertonic glucose versus a balanced fat emulsion system in the face of sepsis is considered.