Acidosis prevents growth hormone-induced growth in experimental uremia

Long-term dietary potential renal acid load during adolescence is prospectively associated with indices of nonalcoholic fatty liver disease in young women

Nonalcoholic fatty liver disease (NAFLD), frequently already present in young subjects, has been linked to reduced growth hormone levels and signaling. Similar hormonal changes occur during metabolic acidosis (MA), which may thus contribute to an increased NAFLD risk. Because subclinical MA can be diet induced, we aimed to examine whether a higher diet-dependent acid load during adolescence is prospectively associated with several currently used NAFLD surrogates in young adulthood. Dietary acidity during adolescence (boys:10-15 y, girls: 9-14 y) was calculated as potential renal acid load (PRAL) from at least three 3-d weighed dietary records according to a published algorithm considering dietary protein and minerals in 145 healthy participants. Routine measurements derived from blood analysis and anthropometric data in participants' young adulthood (18-25 y) were used to determine the NAFLD surrogates alanine-aminotransferase (ALT), hepatic steatosis index (HSI), and fatty liver index (FLI). Sex-stratified linear regression models, adjusted for dietary fiber, saturated fat, protein, and adolescent BMI SD scores, were run with PRAL as the independent variable. Dietary PRAL during puberty was positively associated with ALT (P = 0.02), HSI (P = 0.002), and FLI (P = 0.005) in adult females but not males. Females with an adolescent dietary acid load in the highest tertile had 3.5, 4.4, and 4.5 higher values of ALT, HSI, and FLI as adults, respectively, compared to females with the lowest PRAL. The present findings suggest that higher dietary acidity in adolescence may be prospectively associated with hepatic lipid accumulation in females. Whether this relationship is due to the higher proton load or rather represents an unhealthy dietary pattern requires further investigation.

Consequences and therapy of the metabolic acidosis of chronic kidney disease

Metabolic acidosis is common in patients with chronic kidney disease (CKD), particularly once the glomerular filtration rate (GFR) falls below 25 ml/min/1.73 m(2). It is usually mild to moderate in magnitude with the serum bicarbonate concentration ([HCO(3)(-)]) ranging from 12 to 23 mEq/l. Even so, it can have substantial adverse effects, including development or exacerbation of bone disease, growth retardation in children, increased muscle degradation with muscle wasting, reduced albumin synthesis with a predisposition to hypoalbuminemia, resistance to the effects of insulin with impaired glucose tolerance, acceleration of the progression of CKD, stimulation of inflammation, and augmentation of β(2)-microglobulin production. Also, its presence is associated with increased mortality. The administration of base to patients prior to or after initiation of dialysis leads to improvement in many of these adverse effects. The present recommendation by the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF KDOQI) is to raise serum [HCO(3)(-)] to ≥ 22 mEq/l, whereas Caring for Australians with Renal Impairment (CARI) recommends raising serum [HCO(3)(-)] to >22 mEq/l. Base administration can potentially contribute to volume overload and exacerbation of hypertension as well as to metastatic calcium precipitation in tissues. However, sodium retention is less when given as sodium bicarbonate and sodium chloride intake is concomitantly restricted. Results from various studies suggest that enhanced metastatic calcification is unlikely with the pH values achieved during conservative base administration, but the clinician should be careful not to raise serum [HCO(3)(-)] to values outside the normal range.

Protein restriction for children with chronic renal failure

BACKGROUND

Protein restriction has been prescribed for some time for patients with chronic kidney disease (CKD). The effect of a low protein diet on delaying the progression to end-stage kidney disease (ESKD) in children and its impact on growth and nutrition remains unresolved.

OBJECTIVES

To determine the efficacy of protein restricted diet in delaying the start of maintenance dialysis and maintaining nutrition in children.

SEARCH STRATEGY

Cochrane Renal group trials register, the Cochrane Central register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, reference lists of nephrology textbooks, review articles and relevant trials.

SELECTION CRITERIA

Randomised control trials (RCTs) comparing un-restricted protein diet versus a protein restricted diet (to safe amounts recommended by WHO), with follow-up period of at least six months were included.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies. Statistical analysis were performed using the random effects model. For dichotomous outcome results are expressed as relative risk (RR) with 95% confidence intervals (CI). Where continuous scales of measurement are used to assess the effects of treatment, the mean difference (WMD) was used.

MAIN RESULTS

Two studies (250 children) were identified, 124 received a protein restricted diet and 126 a control diet. No significant differences was found in the number of renal deaths (RR 1.12, 95% CI 0.54 to 2.33), progression of kidney disease (creatinine clearance at two years: WMD 1.47, 95% CI -1.19 to 4.14) or growth (weight - WMD -0.13, 95% CI -1.10 to 0.84; height - WMD -1.99, 95% CI -4.84 to 0.86).

AUTHORS' CONCLUSIONS

Reducing protein intake does not appear to have significant impact in delaying the progression to ESKD in children.

[Physiopathology of the somatotropin axis in chronic renal insufficiency]

Many factors contribute to the growth failure of chronic renal failure: water and electrolytes disturbances, hypertonicity, phosphate or calcium wasting, secondary hyperparathyroidism, anemia, hypertension, metabolic acidosis, and malnutrition. In addition, the pubertal growth spurt is usually stunted. Growth hormone (GH) resistance is observed with low GH binding protein (GHBP) level, and normal or low IGF I levels despite elevated GH level. Elevated IGFBP levels may contribute to a reduced IGF activity, especially in dialysed patients. Glucocorticoid therapy in transplanted patients further contribute to poor growth and inhibited IGF I activity. As conventional treatments have a limited effect to improve growth, adult height is often far below -2 SD. GH therapy has proved to be successful, especially in young children, overpassing the hormonal resistance so that an adult height within the normal range may be reached.

Management of end-stage renal disease in children

OBJECTIVE

To review the medical literature on management of end-stage renal disease (ESRD) and its complications in the pediatric patient.

DATA SOURCES AND STUDY SELECTION

MEDLINE searches (1970-1997) of the English-language literature. Clinical trials and reviews of drug therapy management were included, and bibliographies were reviewed for relevant articles.

DATA SYNTHESIS

Principles of renal replacement therapy in children have been expanded to include maintenance of fluid and electrolyte balance and to manage the complications of ESRD in children. Types of renal replacement and their complications are reviewed. Complications of ESRD are reviewed with emphasis on drug therapy management of anemia of chronic renal failure, growth retardation, and hypertension. A discussion of the use of vitamins and supplements to maintain bone and mineral homeostasis is provided, and specific recommendations for vaccination of children with ESRD are given.

CONCLUSIONS

Children with end-stage renal failure present a unique challenge to the pharmacist. Renal replacement therapy for children with ESRD involves some form of dialysis and an intensive medication regimen. Complications must be treated with appropriate drug therapy. Drug therapy must be monitored closely for dosage adjustment, clinical response, drug interactions, and toxicity. Patients and families must receive continuous education and follow-up to encourage compliance. The pharmacist must work closely with the healthcare team to optimize drug therapy and improve patient education and compliance.

Disturbances of growth hormone-insulin-like growth factor axis and response to growth hormone in acidosis

Severe chronic metabolic acidosis (CMA) in rats is associated with poor food intake and downregulation of growth hormone (GH), insulin-like growth factors (IGFs), and liver receptors; the administration of recombinant GH (rGH) fails to improve the growth failure. In mice with carbonic anhydrase II deficiency (CAD), a model of moderate CMA with food intake close to normal, we studied serum levels of GH, IGFs, and IGF-binding proteins, and the growth response to rGH. CAD was associated with low serum levels of GH in males. Randomized administration of rGH from approximately 5 to approximately 12 wk to CAD mice improved food efficiency and increased serum IGF-I levels, final length, and weight compared with placebo without affecting blood pH. Although administration of rGH also increased linear growth in healthy animals, the effect was less than that in CAD mice and was only observed when started before 6 wk of life. Thus growth failure in CAD mice is associated with a decrease in GH secretion in males but not in females. Long-term administration of rGH increases linear growth in CAD mice despite persistent CMA.

Growth hormone stimulation tests in chronic renal failure with metabolic acidosis

Metabolic acidosis is one of the possible causes of growth retardation in chronic renal failure (CRF). Data about the effect of metabolic acidosis on growth hormone (GH) secretion in CRF are limited. A study was carried out on eight CRF patients, hospitalized because of severe metabolic acidosis, and eight age-matched prepubertal healthy short children. Growth hormone stimulation tests were done with L-dopa and clonidine before or during acidosis therapy and after the correction of metabolic acidosis. The levels of GH were measured by radio-immunoassay. The mean of the peaks of both tests were used for each patient and statistical significance was tested by Mann-Whitney U and Wilcoxon tests. No difference was found between the GH peaks of the two groups during acidosis and after the correction of acidosis (Wilcoxon test, P > 0.05). In view of this data it was concluded that metabolic acidosis has little effect on GH stimulation tests.