Stimulation of human albumin synthesis and gene expression by growth hormone treatment

Effects of growth hormone excess on glycated albumin concentrations: Analysis in acromegalic patients

BACKGROUND

Glycated albumin (GA) does not reflect glycemic control in patients with disorders of albumin metabolism. In the present study, we examined GA concentrations in acromegalic patients with growth hormone (GH) excess.

METHODS

We studied the hormonal status of 29 acromegalic patients (10 patients had diabetes mellitus and the remaining 19 patients were non-diabetic), 20 patients with type 2 diabetes mellitus and 38 non-diabetic subjects matched for age, sex and body mass index.

RESULTS

Serum GA concentrations, but not those of fasting plasma glucose, 2-h post-load plasma glucose and HbA1c, were significantly higher in non-diabetic acromegalic patients compared with non-diabetic control subjects. Serum GA concentrations, but not those of fasting plasma glucose and HbA1c, were significantly higher in diabetic acromegalic patients compared with patients with type 2 diabetes mellitus.

CONCLUSIONS

This is the first report describing higher GA concentrations in acromegalic patients relative to plasma glucose concentrations. Special care should be taken when evaluating glycemic control using GA because acromegaly is frequently complicated with diabetes mellitus.

Protein and carbohydrate supplementation after exercise increases plasma volume and albumin content in older and young men

This study examined whether increased plasma volume (PV) and albumin content (Alb(cont)) in plasma for 23 h after exercise were attenuated in older subjects compared with in young adult subjects, and if this attenuation abated by supplementation with protein and carbohydrate (CHO) immediately after exercise. Eight moderately active older (approximately 68 yr) and 8 young (approximately 21 yr) men performed two trials: control (CNT) and Pro-CHO in which subjects consumed placebo (0.5 kcal, 0 g protein, 0.5 mg Na(+) in 3.2 ml total fluid volume/kg body wt) or protein and CHO mixture (3.2 kcal, 0.18 g protein, 0.5 mg Na(+) in 3.2 ml total fluid volume/kg body wt) supplementations, respectively, immediately after high-intensity interval exercise for 72 min [8 sets of 4 min at 70-80% peak oxygen consumption rate (Vo(2peak)) intermitted by 5 min at 20% Vo(2peak)]. PV, Alb(cont), and plasma globulin content (Glb(cont)) were measured before exercise, at the end of exercise, every hour from the 1st to the 5th hour after exercise, and at the 23rd hour after exercise. From 12 h before the start to the end of experiment, food intake was controlled to the age-matched recommended dietary allowances. We found that during the first 4 h after exercise in CNT, Alb(cont) recovered less in the older than the young group by approximately 0.04 g/kg (P < 0.05), while it generally recovered more with Pro-CHO than CNT by approximately 0.09 and approximately 0.04 g/kg in the young and older group, respectively, accompanied by a greater increase in PV by approximately 1 and approximately 2 ml/kg, respectively, during the 23 h after exercise (P < 0.05). Glb(cont) remained constant throughout the experiment in both trials for both age groups. Thus the attenuated responses of Alb(cont) and PV after exercise in older subjects were restored by protein and CHO supplementation immediately after exercise, similarly to young subjects.

Albumin synthesis in preterm infants on the first day of life studied with [1-13C]leucine

Albumin is the major binding protein in the human neonate. Low production of albumin will lower its transport and binding capacity. This is especially important in preterm infants, in whom albumin binds to potentially toxic products such as bilirubin and antibiotics. To study the metabolism of plasma albumin in preterm infants, we administered a 24-h constant infusion of [1-(13)C]leucine to 24 very low birth weight (VLBW) infants (28.4 +/- 0.4 wk, 1,080 +/- 75 g) on the first day of life. The caloric intake consisted of glucose only, and therefore amino acids for albumin synthesis were derived from proteolysis. The fractional synthesis rate (FSR) of plasma albumin was 13.9 +/- 1.5%/day, and the absolute synthesis rate was 148 +/- 17 mg x kg(-1) x day(-1). Synthesis rates were significantly lower (P<0.03) in infants showing intrauterine growth retardation. Albumin synthesis increased with increasing SD scores for gestation and weight (P<0.05). The FSR of albumin tended to increase by 37% after administration of antenatal corticosteroids to improve postnatal lung function (P=0.09). We conclude that liver synthetic capacity is well developed in VLBW infants and that prenatal corticosteroids tend to increase albumin synthesis. Decreased weight gain rates in utero have effects on protein synthesis postnatally.

Clinical evidence of growth hormone for patients undergoing abdominal surgery: Meta-analysis of randomized controlled trials

AIM: To assess the effectiveness and safety of perioperative growth hormone (GH) in patients undergoing abdominal surgery.

METHODS: We searched the following electronic databases: MEDLINE, EMBASE, the Cochrane Controlled Trials Register, Chinese Bio-medicine Database. The search was undertaken in February 2003. No language restrictions were applied. Randomized controlled trials (RCT) comparing GH with placebo in patients undergoing abdominal surgery were extracted and evaluated. Methodological quality was evaluated using the Jadad scale.

RESULTS: Eighteen trials involving 646 patients were included. The combined results showed that GH had a positive effect on improving postoperative nitrogen balance (standardized mean difference [SMD] = 3.37, 95%CI [2.46, 4.27], P < 0.00001), and decreasing the length of hospital stay (weighted mean difference [WMD] = -2.07, 95%CI [-3.03, -1.11], P = 0.00002), and reducing the duration of postoperative fatigue syndrome (SMD = -1.83, 95%CI [-2.37, -1.30], P < 0.00001), but it could increase blood glucose levels (WMD = 0.91, 95%CI [0.56, 1.25], P < 0.00001).

CONCLUSION: GH for patients undergoing abdominal surgery is effective and safe, if blood glucose can be controlled well. Further trials are required with a sufficient size to account for clinical heterogeneity and to measure other important outcomes such as infection, morbidity, mortality, fluid retention, immunomodulatory effects, and tumor recurrence.

The synthesis rate of albumin decreases during laparoscopic surgery

In previous studies, a decline in total liver protein synthesis during elective laparoscopic surgery has been observed. However, when albumin synthesis was measured in parallel no apparent influence of the procedure was detected. The aim of the present study was to specifically investigate the effect of a laparoscopic procedure on albumin synthesis. Female (n = 9) patients scheduled for elective laparoscopic cholecystectomy as a consequence of cholecystolithiasis were investigated. The fractional synthesis rate (FSR) of albumin was investigated twice in each patient, before and during surgery (2-3 h apart), employing L-[2H5]phenylalanine and gas chromatography mass spectrometry. The FSR of albumin decreased from 7.3 +/- 1.2% per day before surgery to 6.2 +/- 1.4% per day during the procedure (P<0.01), whereas the corresponding absolute synthesis rates of albumin decreased from 114 +/- 24 to 86 +/- 16 mg kg(-1) day(-1), respectively (P<0.001). In conclusion, the synthesis rate of albumin decreased during a laparoscopic surgery procedure. However, the characteristics for this decrease differ from those previously observed for total liver protein synthesis.

The role of visceral proteins in the nutritional assessment of intensive care unit patients

PURPOSE OF REVIEW

This review analyses the recently published literature focusing on nutritional assessment in intensive care unit patients. The metabolic response to nutritional intervention is difficult to evaluate in critically ill patients whose body weight is influenced largely by massive fluid administration or losses. Visceral protein plasma levels have been proposed for this purpose, because they reflect hepatic synthesis in response to nutrient supply. However, in acute inflammatory states, liver activity is converted to the synthesis of acute-phase response proteins, resulting in a dramatic drop in visceral proteins, despite nutritional support.

RECENT FINDINGS

The data regarding visceral protein levels were examined in relation to nutritional supplementation, and compared with other nutritional parameters and clinical outcomes. Transthyretin and retinol-binding protein levels seem to be the most sensitive to nutritional intervention. They are also the earliest to rise at the decrease of acute-phase protein levels, therefore representing a good index of the reversing reprioritization of hepatic protein synthesis. An inconsistent relationship was found between visceral protein plasma levels and clinical outcome in intensive care unit patients, probably because of the difficulty in demonstrating clearly a beneficial effect of nutritional supplementation in highly catabolic conditions.

SUMMARY

In the acute stage of critical illness, the bi-weekly measurement of transthyretin together with acute-phase response protein plasma levels seems to be a 'window' on the metabolic condition (anabolism versus catabolism). However, only in the presence of stable inflammatory parameters do transthyretin levels reflect the adequacy of nutritional coverage.

Liver protein synthesis in physiology and in disease states

Liver protein synthesis is usually estimated in humans by measuring the synthesis rates of major exported liver proteins. Among these, the synthesis rates of albumin and fibrinogen have been more commonly studied. Recently, it was reported that several physiological stimuli such as physical exercise followed by recovery in the upright position, active and passive ascent to high altitude or life-style habits like vegetarian diet or smoking affect the synthesis rates of albumin and fibrinogen. Among disease states, the most recent literature addresses the effects of kidney diseases (hemodialysis, nephrotic syndrome), type 2 diabetes mellitus and growth hormone administration to critically ill patients and to patients undergoing laparoscopic colecystectomy. The results of these studies have clarified several aspects of the regulation of liver protein synthesis in humans and raise open questions that will stimulate the future research in the area.