Is low birth weight a risk factor for the development of diabetic nephropathy in patients with type 1 diabetes? A population-based case-control study

Birth Weight and Susceptibility to Chronic Kidney Disease

The worldwide prevalence of noncommunicable diseases (NCDs) is projected to increase substantially over the next few decades. Chronic kidney disease (CKD) is a key determinant of poor health outcomes for major NCD. Genetic predisposition and environmental exposures are contributory factors, but increasingly, it is being recognized that fetal development is also an important modulator of the NCD risk. Low birth weight (LBW) and CKD affect more disadvantaged populations and ethnic minorities and, therefore, causes a disproportionate burden on the poor. Human nephron number is highly variable and may range from under half a million to almost over two million. Significant variability is already present at birth, highlighting the importance of early nephrogenesis. Nearly 60% of nephrons are developed in the third-trimester of pregnancy. Nephron numbers increase in proportion to birth weight and gestational age. This wide-variability probably contributes to individual susceptibility to develop CKD where individuals with nephron numbers on the lower side of the spectrum are those at higher risk of developing kidney dysfunction at higher rate and progress more toward end-stage CKD. This article aims at discussing LBW and the susceptibility to CKD. Furthermore, in postnatal environment, the weight gain or change at adult life increases the metabolic demand and determines the phenotypic expression of disease along with the spectrum of nephron number. Hence, a cycle of hyperfiltration mechanism of these nephrons leads to proteinuria, glomerulo- sclerosis, and progressive development of larger glomeruli, a greater risk of proteinuria and progressive CKD. Therefore, LBW offspring are at risk of developing CKD (defined as albuminuria, a reduced glomerular filtration rate, or renal failure) in later life. Furthermore, the impact of prenatal programming is expected to be compounded with age, and the association of LBW with the risk of CKD seen in younger adults may become greater with age. It would be prudent, to adopt policies of intensified life-long surveillance of LBW people, anticipating this risk.

Effect of birth weight on adulthood renal function: A bias-adjusted meta-analytic approach

While the association between low birth weight (LBW; <2500 g) and development of adult chronic renal disease (CKD) is inconsistently reported, less information is available regarding association of high birth weight (HBW; ≥4000 g) with CKD. We undertook a systematic review and meta-analysis on studies published before 30 September 2015 and report associations between birth weight and renal function. Blood (glomerular filtration rate (GFR)) and urine (microalbuminuria/albumin excreation rate (AER)/urinary albumin creatinine ratio (ACR)) parameters were used to define CKD. Three different effect size estimates were used (odds ratio, regression coefficient and mean difference). The odds of developing CKD in the life course among those born LBW was 1.77 (95% CI: 1.42, 2.20) times and 1.68 (1.27, 2.33) times, assessed by blood and urine parameters respectively. Higher risk was also observed among Asian and Australian populations (blood: OR 2.68; urine: OR 2.28), individuals aged ≤30 years (blood: OR 2.30; urine: OR 1.26), and ≥50 years (blood: OR 3.66; urine: OR 3.10), people with diabetes (blood: OR 2.51), and aborigines (urine: OR 2.32). There was no significant association between HBW and CKD. For every 1 kg increase in BW, the estimated GFR increased by 2.09 mL/min per 1.73 m(2) (1.33-2.85), and it was negatively associated with LogACR (ß -0.07, 95% CI: -0.14, 0.00). LBW inborn had lower mean GFR -4.62 (-7.10, -2.14) compared with normal BW. Findings of this study suggest that LBW increased the risk of developing CKD, and HBW did not show any significant impact.

Low birthweight and chronic kidney disease

Low birthweight reflects the congenital defects of organs, which is associated with chronic kidney disease through its direct influence on nephron number and function, also through related metabolic disease-induced kidney damage. We reviewed the current evidence regarding the role of low birthweight in the pathogenesis of chronic kidney disease.

Is low birth weight an antecedent of CKD in later life? A systematic review of observational studies

BACKGROUND

There has been considerable interest in the hypothesis that low birth weight may be a marker of impaired nephrogenesis and that this is causally related to chronic kidney disease (CKD).

STUDY DESIGN

Systematic review and meta-analysis of observational studies.

SETTING & POPULATION

Studies of the relationship between birth weight and CKD published before February 1, 2008, were identified by using electronic searches.

SELECTION CRITERIA

All studies that had collected data for birth weight and kidney function at greater than 12 months of age were eligible for inclusion, except for studies of extremely low-birth-weight infants, very premature infants, or toxic exposure in utero. STUDY FACTOR: Birth weight.

OUTCOMES

CKD defined as albuminuria, low estimated glomerular filtration rate (<60 mL/min/1.73 m(2) or < 10th centile for age/sex), or end-stage renal disease.

RESULTS

We analyzed 31 relevant cohort or case-control studies with data for 49,376 individuals and data for 2,183,317 individuals from a single record-linkage study. Overall, 16 studies reported a significant association between low birth weight and risk of CKD and 16 observed a null result. The combination of weighted estimates from the 18 studies for which risk estimates were available (n = 46,249 plus 2,183,317 from the record linkage study) gave an overall odds ratio (OR) of 1.73 (95% confidence interval [CI], 1.44 to 2.08). Combined ORs were consistent in magnitude and direction for risks of albuminuria (OR, 1.81; 95% CI, 1.19 to 2.77), end-stage renal disease (OR, 1.58; 95% CI, 1.33 to 1.88), or low estimated glomerular filtration rate (OR, 1.79; 95% CI, 1.31 to 2.45).

LIMITATIONS

A reliance on published estimates and estimates provided on request rather than individual patient data and the possibility of reporting bias.

CONCLUSIONS

Existing data indicate that low birth weight is associated with subsequent risk of CKD, although there is scope for additional well-designed population-based studies with accurate assessment of birth weight and kidney function and consideration of important confounders, including maternal and socioeconomic factors.

Having one kidney does not accelerate the rate of development of diabetic nephropathy lesions in type 1 diabetic patients

OBJECTIVE

Reduced nephron number is hypothesized to be a risk factor for chronic kidney disease and hypertension. Whether reduced nephron number accelerates the early stages of diabetic nephropathy is unknown. This study investigated whether the rate of development of diabetic nephropathy lesions was different in type 1 diabetic patients with a single (transplanted) kidney compared with patients with two (native) kidneys.

RESEARCH DESIGN AND METHODS

Three groups of volunteers were studied: 28 type 1 diabetic kidney transplant recipients with 8-20 years of good graft function, 39 two-kidney patients with duration of type 1 diabetes matched to the time since transplant in the one-kidney group, and 30 age-matched normal control subjects. Electron microscopic morphometry was used to estimate glomerular structural parameters on 3.0 +/- 1.4 glomeruli per biopsy.

RESULTS

In the one- versus two-kidney diabetic subject groups, respectively, serum creatinine (means +/- SD 1.3 +/- 0.4 vs. 0.9 +/- 0.2 mg/dl; P < 0.001), systolic blood pressure (133 +/- 13 vs. 122 +/- 11 mmHg; P < 0.001), and albumin excretion rate (median [range] 32.1 microg/min [2-622] vs. 6.8 microg/min [2-1,495]; P = 0.006) were higher. There were no differences in the one- versus two-kidney diabetic subject groups, respectively, in glomerular basement membrane width (median [range] 511 nm [308-745] vs. 473 nm [331-814]), mesangial fractional volume (mean +/- SD 0.30 +/- 0.06 vs. 0.27 +/- 0.07), mesangial matrix fractional volume (0.16 +/- 0.05 vs. 0.16 +/- 0.06), and mesangial matrix fractional volume per total mesangium (0.61 +/- 0.07 vs. 0.64 +/- 0.09). However, these glomerular structural parameters were statistically significantly higher in both diabetic subject groups compared with normal control subjects. Results were similar when patients receiving ACE inhibitors were excluded from the analyses.

CONCLUSIONS

Reduced nephron number is not associated with accelerated development of diabetic glomerulopathy lesions in type 1 diabetic patients.

Consequences of Intrauterine Growth Restriction for the Kidney

Low birth weight due to intrauterine growth restriction is associated with various diseases in adulthood, such as hypertension, cardiovascular disease, insulin resistance and end-stage renal disease. The purpose of this review is to describe the effects of intrauterine growth restriction on the kidney. Nephrogenesis requires a fine balance of many factors that can be disturbed by intrauterine growth restriction, leading to a low nephron endowment. The compensatory hyperfiltration in the remaining nephrons results in glomerular and systemic hypertension. Hyperfiltration is attributed to several factors, including the renin-angiotensin system (RAS), insulin-like growth factor (IGF-I) and nitric oxide. Data from human and animal studies are presented, and suggest a faltering IGF-I and an inhibited RAS in intrauterine growth restriction. Hyperfiltration makes the kidney more vulnerable during additional kidney disease, and is associated with glomerular damage and kidney failure in the long run. Animal studies have provided a possible therapy with blockage of the RAS at an early stage in order to prevent the compensatory glomerular hyperfiltration, but this is far from being applicable to humans. Research is needed to further unravel the effect of intrauterine growth restriction on the kidney.

The effect of intrauterine environment and low glomerular number on the histological changes in diabetic glomerulosclerosis

AIMS/HYPOTHESIS

We tested the hypothesis that diabetic glomerulosclerosis would develop more rapidly in animals with fewer glomeruli.

METHODS

We studied the female offspring of Wistar rats that had been fed a low-protein diet (LPD) containing 6% protein or a normal-protein diet (NPD) containing 18% protein during pregnancy. Streptozotocin diabetes was induced at 12 weeks and animals were killed at 40 weeks.

RESULTS

Non-diabetic LPD offspring were of lower birthweight than the NPD offspring (5.19+/-0.64 vs 6.45+/-0.67 g, p<0.001) and had fewer glomeruli (27,402+/-3,137 vs 34,203+/-6,471, p<0.05). Glomerular volume correlated inversely with glomerular number (r=-0.64, p=0.035), but total glomerular filtration surface area was reduced in the LPD animals (4,770+/-541 vs 5,779+/-1,302 mm(2), p=0.05). Other renal structural and functional parameters were similar. In LPD and NPD diabetic animals, glomerular volume and basement membrane width were significantly increased compared to their respective controls. Podocyte density was lowest in the LPD diabetic animals (not significant), and the area covered by each podocyte was greater in the LPD diabetic group (2.40+/-0.693 x10(-3) mm(2)) than in the LPD control group (1.68+/-0.374 x10(-3) mm(2), p<0.001) and in the NPD diabetic animals (1.71+/-0.291 x 10(-3) mm(2), p<0.05). There was no difference in any other structural or functional parameter between the LPD and NPD diabetic animals.

CONCLUSIONS/INTERPRETATION

A decrease in glomerular number was not deleterious to renal structure and function over 40 weeks in this animal model. Further work in models with progressive renal impairment and hypertension is necessary to clarify the impact of glomerular number on the development of renal disease.

Early glycemic control, age at onset, and development of microvascular complications in childhood-onset type 1 diabetes: a population-based study in northern Sweden

OBJECTIVE

The aim of this work was to study the impact of glycemic control (HbA(1c)) early in disease and age at onset on the occurrence of incipient diabetic nephropathy (MA) and background retinopathy (RP) in childhood-onset type 1 diabetes.

RESEARCH DESIGN AND METHODS

All children, diagnosed at 0-14 years in a geographically defined area in northern Sweden between 1981 and 1992, were identified using the Swedish Childhood Diabetes Registry. From 1981, a nationwide childhood diabetes care program was implemented recommending intensified insulin treatment. HbA(1c) and urinary albumin excretion were analyzed, and fundus photography was performed regularly. Retrospective data on all 94 patients were retrieved from medical records and laboratory reports.

RESULTS

During the follow-up period, with a mean duration of 12 +/- 4 years (range 5-19), 17 patients (18%) developed MA, 45 patients (48%) developed RP, and 52% had either or both complications. A Cox proportional hazard regression, modeling duration to occurrence of MA or RP, showed that glycemic control (reflected by mean HbA(1c)) during the follow-up was significantly associated with both MA and RP when adjusted for sex, birth weight, age at onset, and tobacco use as potential confounders. Mean HbA(1c) during the first 5 years of diabetes was a near-significant determinant for development of MA (hazard ratio 1.41, P = 0.083) and a significant determinant of RP (1.32, P = 0.036). The age at onset of diabetes significantly influenced the risk of developing RP (1.11, P = 0.021). Thus, in a Kaplan-Meier analysis, onset of diabetes before the age of 5 years, compared with the age-groups 5-11 and >11 years, showed a longer time to occurrence of RP (P = 0.015), but no clear tendency was seen for MA, perhaps due to lower statistical power.

CONCLUSIONS

Despite modern insulin treatment, >50% of patients with childhood-onset type 1 diabetes developed detectable diabetes complications after approximately 12 years of diabetes. Inadequate glycemic control, also during the first 5 years of diabetes, seems to accelerate time to occurrence, whereas a young age at onset of diabetes seems to prolong the time to development of microvascular complications.