Microalbuminuria as a screening tool in cystic fibrosis-related diabetes

Retinopathy and microalbuminuria are common microvascular complications in cystic fibrosis-related diabetes

AIMS

To study the prevalence of microvascular complications and renal changes associated with cystic fibrosis-related diabetes (CFRD).

METHODS

This retrospective cohort study was conducted at the West Midlands Adult Cystic Fibrosis centre, United Kingdom. Data regarding age, sex, microalbuminuria, retinopathy neuropathy, and biochemical results were collected for all people with CFRD who had an annual review from 1 January 2018 to 31 December 2018 at the centre. Descriptive statistics were analysed using STATAv15.1.

RESULTS

A total of 189 patients were included, of which 56.6% were male and median age (interquartile range) was 33 (27-39) years; 79.4% (150/189) had their annual review in 2018. Those with a biochemically impaired renal function numbered 7.2% (13/180) and 22.7% (32/141) had microalbuminuria; 17.2% (10/58) had diabetes related retinopathy. No one in our cohort had diabetic ulcers; however, 10.3% (13/126) had absent foot pulses.

CONCLUSION

We found a higher prevalence of microalbuminuria compared with retinopathy in a large cohort of cystic fibrosis adults. This study demonstrates the need for regular specialist follow-up to facilitate early identification of such complications and a long-term prospective cohort to understand underlying mechanisms.

Cystic fibrosis related diabetes

Improved life expectancy in cystic fibrosis (CF) has led to an expanding population of adults with CF, now representing almost 50 % of the total CF population. This creates new challenges from long-term complications such as diabetes mellitus (DM), a condition that is present in 40 %-50 % of adults with CF. Cystic fibrosis-related diabetes (CFRD) results from a primary defect of insulin deficiency and although sharing features with type 1 (DM1) and type 2 diabetes (DM2), it is a clinically distinct condition. Progression to diabetes is associated with poorer CF clinical outcomes and increased mortality. CFRD is not associated with an increased risk of cardiovascular disease and the prevalence of microvascular complications is lower than DM1 or DM2. Rather, the primary goal of insulin therapy is the preservation of lung function and optimization of nutritional status. There is increasing evidence that appropriate screening and early intervention with insulin can reverse weight loss and improve pulmonary function. This approach may include targeting postprandial hyperglycemia not detected by standard diagnostic tests such as the oral glucose tolerance test. Further clinical research is required to guide when and how much to intervene in patients who are already dealing with the burden of one chronic illness.

High-dose ibuprofen is not associated with increased biomarkers of kidney injury in patients with cystic fibrosis

High-dose ibuprofen (IBU) may slow the decline of lung function in patients with cystic fibrosis (CF), but its use has been limited due to concerns over renal and gastrointestinal toxicity. In this pilot study, we examined the association of IBU with markers of acute kidney injury (AKI) in patients with CF. The effect of aminoglycoside (AG) exposure on AKI biomarkers was also examined. The AKI markers, kidney injury molecule-1 (KIM), N-acetyl-β-glucosaminidase (NAG) and urine protein, normalized for creatinine, were chosen as they are more sensitive indicators of kidney injury than changes in serum creatinine. Urine samples from 52 patients, 26 from patients who were treated with IBU, were analyzed. There was no significant association between IBU treatment and KIM-1, NAG or protein levels, compared to patients never treated with IBU. While there was an association between AG courses and KIM-1 levels, there were no differences in biomarker levels between IBU and non-IBU groups with respect to AG courses. These preliminary results suggest that IBU treatment in patients with CF may be safe with respect to renal toxicity.

Microalbuminuria in patients with cystic fibrosis

OBJECTIVE

We previously found that microalbuminuria (MA) is present in 14% of patients with long-standing cystic fibrosis-related diabetes (CFRD). However, others have reported much higher rates of MA in CF patients with and without diabetes (32-67%), suggesting this test is not sufficiently specific for diabetic nephropathy screening in CF. We investigated transient (TMA) and persistent (PMA) microalbuminuria in CF patients to resolve these contradictory findings.

RESEARCH DESIGN AND METHODS

We reviewed 1,449 outpatient urinary albumin measurements from 467 patients aged ≥10 years, which were collected over a decade. TMA was defined as a single episode of MA that subsequently was resolved. PMA was defined as two consecutive or two out of three consecutive measurements in the MA range.

RESULTS

The prevalence of TMA that subsequently was resolved in CF patients was similar to the general population. It was found in 7.6% of patients, including 5% of youth (aged 10-17 years) and 9% of adults. PMA was found in 6.1% of the overall CF population, including 2% of youth and 8% of adults. The odds of PMA were increased sevenfold in patients with CFRD (95% CI 2.5-20, P=0.0002) and 48-fold in patients with both CFRD and organ transplant (95% CI 13-177, P<0.0001). The five patients with PMA in the absence of CFRD or transplant included two youths with presumed benign orthostatic MA and three adults with hypertension.

CONCLUSIONS

The spot urine albumin-to-creatinine ratio is specific enough to be a valid screening test for diabetic kidney disease in CFRD.

Renal function in pediatric cystic fibrosis patients in the first decade of life

With increasing life expectancy and the need for lung transplantation in the cystic fibrosis (CF) population, there are increasing reports of chronic kidney disease (CKD). However, values for baseline or longitudinal glomerular filtration rate (GFR) as measured by exogenous clearance markers are lacking in this population. Retrospective cross-sectional study in 2 to 18-year-olds cared for at a single CF center who had a GFR measured by plasma disappearance of Technetium-99 m diethylenetriaminepentaacetic acid (mGFR). The primary outcome was evidence of renal dysfunction as defined by CKD stage II or below (mGFR <90 ml/min/1.73 m(2), persistent abnormalities in urinary sediment, abnormal renal imaging). Of 63 patients evaluated, four had apparent renal dysfunction, one demonstrated decreased mGFR, and three others had persistent microscopic hematuria. The mean mGFR was substantially higher (140 ± 24 ml/min/1.73 m(2)) than expected or previously reported for healthy children. We did not demonstrate the presence of significant renal impairment after limited aminoglycoside exposure in the first decade following diagnosis with CF. However, we did document the presence of glomerular hyperfiltration in a significant proportion of our CF patients.

Pharmacotherapy of diabetes in cystic fibrosis patients

IMPORTANCE OF THE FIELD

Cystic fibrosis-related diabetes (CFRD) is a unique type of diabetes. In this article I review the pathophysiology of CFRD to gain insight as to why these patients have clinical features of both type 1 and 2 diabetes (DM). The reader will also learn that, although CFRD is different from type 1 and 2 DM, the development of diabetes-induced complications is similar to other types of DM. These complications can include retinopathy, nephropathy and neuropathy resulting from uncontrolled hyperglycemia; however, hyperglycemia and/or insulin deficiency in people with CFRD may exacerbate underlying CF problems, such as decreased pulmonary function and weight loss.

AREAS COVERED IN THIS REVIEW

Review medical therapy of CFRD including the over-riding goal of maintaining blood glucose levels in a range as close to normal as possible. The other important goal for diabetes management is to prevent diabetes complications and to encourage psychological wellbeing of the patient. However, as reviewed in this article, the underlying medical condition of people with CF and the basic metabolic differences caused by the disease often provide challenges in maintaining optimal diabetes control.

WHAT THE READER WILL GAIN

The reader will gain an understanding of how CFRD physically affects the patient with CF and the various pharmacologic therapies available for treatment of this type of diabetes. Furthermore they will gain insight into areas where more research is needed.

TAKE HOME MESSAGE

Cystic fibrosis-related diabetes is unique to CF and thus deserves disease specific medical therapy.

Renal impairment in children with cystic fibrosis

BACKGROUND

Due to the improvement in life expectancy in cystic fibrosis (CF), co-morbidities such as renal function impairment may be more frequent.

AIM

To determine the prevalence of renal disease in children with CF and to identify associated risk factors.

METHODS

A single-center retrospective study analyzing the genetic, clinical and therapeutic characteristics of 112 children. The estimated glomerular filtration rate (GFR), microalbuminuria and lithiasic risk factors were assessed.

RESULTS

The median calculated GFR (Schwartz) was 123, 161 and 155ml/min/1.73m(2) in children aged 1, 6 and 15years, respectively. The cumulative dose of aminoglycosides was not correlated to GFR. Microalbuminuria was present in 22/38 patients. Hyperoxaluria was observed in 58/83 patients and was associated with a severe genotype, pancreas insufficiency and liver disease. Hypercalciuria, hyperuricuria and hypocitraturia were identified in 16/87, 15/83 and 57/76 patients, respectively.

CONCLUSION

Renal impairment in CF has various presentations. There appears to be low levels of renal impairment in children with CF. However, the risk of oxalocalcic urolithiasis is enhanced, and GFR may be underestimated by the Schwartz formula. Further studies using measured GFR techniques are thus warranted.

[Renal diseases in cystic fibrosis]

Patients with cystic fibrosis (CF) show a continuing improvement in their life expectancy thanks to advances in knowledge of this disorder, allowing better multidisciplinary routine monitoring and earlier therapeutic interventions. Likewise, more than of 40% of these patients are adults and CF is no more only a pediatric disease. Due to their higher life expectancy, CF patients present new and unusual complications that were not recorded before. Among them, some renal disorders have to be added to the CF-related renal diseases. They are due to frequent and prolonged exposure to various potentially nephrotoxic factors that need to be taken into account early enough in order to avoid renal failure : essentially risk factors for kidney stones formation, bacterial infections with their associated immune complexes diseases, nephrotoxic effects of antibiotics, diabetes mellitus. Because we observed a case of IgA glomerulonephritis in a 35-year-old patient with cystic fibrosis, we have searched about all these renal consequences due to this affection and here report them.

Proteinuria in cystic fibrosis: a possible correlation between genotype and renal phenotype

OBJECTIVE: To assess proteinuria in patients with cystic fibrosis (CF), and to correlate proteinuria with genotype, CF-related diabetes and disease severity. METHODS: A prospective study was carried out over a six-month period and involving 22 CF patients. After the collection and analysis of 24-h urine samples, the patients were divided into two subgroups: protein excretion < 150 mg/day (low-proteinuria); and protein excretion > 150 mg/day (highproteinuria). Patient charts were reviewed to obtain data on genotype and CF-related diabetes. Disease severity was assessed based on acute exacerbations in the last six months and FEV1 measured during the study period. To assess the correlation between genotype and proteinuria, the two main mutations (ΔF508 and R334W) were evaluated. Due to the existence of genotype ΔF508/R334W, two categories were created to enable statistical analysis, ΔF508 being evaluated in category 1 and R334W being evaluated in category 2. RESULTS: The ΔF508 mutation tended to be associated with normal protein excretion: 100% of the low-proteinuria subgroup patients were considered ΔF508 in category 1, compared with 86.7% in category 2. Protein excretion tended to be higher in patients with the R334W mutation: 60.0% of the high-proteinuria subgroup patients were considered R334W in category 1, compared with 80.0% in category 2 (p = 0.009 and p = 0.014, respectively). No significant association was found for any of the other variables. CONCLUSIONS: The results suggest that genotype is associated with renal phenotype, depending on the mechanism by which the genotype alters the function of the cystic fibrosis transmembrane conductance regulator gene.

Intensive care management of the patient with cystic fibrosis

Cystic fibrosis was previously thought to be a disease of childhood. With a better understanding of this condition along with improvements in therapy, patients with cystic fibrosis are now living well into adulthood. The aim of this article is to familiarize the intensive care unit physician with cystic fibrosis care, to discuss complications associated with cystic fibrosis specifically related to the intensive care unit, and to detail the current recommendations for the clinical management of the patient with cystic fibrosis. With advancing disease, the most severely affected organs are the lungs. Obstruction, infection, and inflammation contribute to the decline of pulmonary function, ultimately leading to death. Some patients may be eligible for lung transplantation, but choosing wisely will affect posttransplant survival. Because other organs are affected by the genetic defect and associated treatments, serious complications related to the liver, pancreas, intestines, and kidneys must be considered by the intensivist faced with a patient with cystic fibrosis. As practitioners, the fact that not all patients will survive and help our patients and families gracefully through the end-of-life process should be accepted.

Diabetes mellitus in patients with cystic fibrosis

Cystic fibrosis-related diabetes (CFRD) is the principal extra-pulmonary complication of cystic fibrosis, occurring in 15-30% of adult cystic fibrosis patients. The number of cystic fibrosis patients who develop diabetes is increasing in parallel with increases in life expectancy. The aim of this study was to review the physiopathology, clinical presentation, diagnosis and treatment of CFRD. A bibliographic search of the Medline and Latin American and Caribbean Health Sciences Literature databases was made. Articles were selected from among those published in the last twenty years. Insulin deficiency, caused by reduced beta-cell mass, is the main etiologic mechanism, although insulin resistance also plays a role. Presenting features of type 1 and type 2 diabetes, CFRD typically affects individuals of approximately 20 years of age. It can also be accompanied by fasting, non-fasting or intermittent hyperglycemia. Glucose intolerance is associated with worsening of nutritional status, increased morbidity, decreased survival and reduced pulmonary function. Microvascular complications are always present, although macrovascular complications are rarely seen. An oral glucose tolerance test is recommended annually for patients > or = 10 years of age and for any patients presenting unexplained weight loss or symptoms of diabetes. Patients hospitalized with severe diseases should also be screened. If fasting hyperglycemia persists for more than 48 h, insulin therapy is recommended. Insulin administration remains the treatment of choice for diabetes and fasting hyperglycemia. Calories should not be restricted, and patients with CFRD should be managed by a multidisciplinary team.

O diabetes melito na fibrose cística: uma comorbidade cada vez mais freqüente

O diabetes melito (DM) é a principal comorbidade relacionada à fibrose cística (FC) e costuma acontecer após os 15 anos de idade, associando-se ao aumento da morbimortalidade. Sua fisiopatologia inclui destruição do tecido exócrino, insuficiência endócrina e aumento da resistência insulínica, determinando inicialmente a alteração da cinética secretora da insulina, até o comprometimento de sua secreção total. A hiperglicemia pós-prandial é a alteração clínica mais precoce e sintomas do DM podem não ser reconhecidos. A investigação anual deve ser realizada por meio da glicemia de jejum ou de glicemias ao acaso e do teste oral de tolerância à glicose (OGTT). São reconhecidas duas categorias de diabetes relacionadas à FC: o DRFC sem hiperglicemia de jejum (HJ) (glicemia de jejum < 126 mg/dL e glicemia de 2 horas OGTT > 200 mg/dL) e DRFC com HJ (glicemia de jejum > 126 mg/dL). O tratamento inclui o manejo nutricional especializado e a correção da hiperglicemia. A insulinoterapia é recomendada para a categoria DRFC com HJ, não existindo ainda evidências do benefício de drogas secretagogas ou sensibilizantes da ação insulínica.

Cystic fibrosis and renal disease: a case report

Background

Cystic fibrosis (CF) is an autosomal recessive disease that is predominantly seen in the Caucasian population and involves multiple organs. Traditionally it has been thought that the kidney is the only organ which does not seem to be generally affected by the disease although the cystic fibrosis transmembrane conductance regulator (CFTR) gene is expressed in the kidney.

Case presentation

We report the case of an 11 year old boy with cystic fibrosis and nephrotic syndrome and review the literature that describes nephrotic syndrome and renal involvement in cystic fibrosis.

Conclusion

With continued advances in the management of cystic fibrosis and improvement in life expectancy, several unrecognized co-morbidities are expected to emerge. It is important to screen patients for possible co-morbidities. Urine analysis may be helpful in this group of patients and any proteinuria should raise the suspicion of cystic fibrosis-related renal disease.

Microvascular complications in cystic fibrosis-related diabetes

OBJECTIVE

The incidence of cystic fibrosis-related diabetes (CFRD) and the prevalence of diabetic microvascular complications were determined at the University of Minnesota.

RESEARCH DESIGN AND METHODS

Cystic fibrosis patients have undergone annual oral glucose tolerance testing since 1990. Database review was performed to determine diabetes duration and the results of annual urine albumin-to-creatinine ratio (U(alb:Cr)) screening and dilated retinal exams. In addition, 59 individuals underwent detailed retinopathy, nephropathy, neuropathy, and gastroenteropathy screening.

RESULTS

During 1990-2005, 775 patients aged > or = 6 years were followed. CFRD was diagnosed by an oral glucose tolerance test or fasting hyperglycemia in 285 subjects (52% female), 64% of whom had fasting hyperglycemia. Most patients with CFRD without fasting hyperglycemia progressed to CFRD with fasting hyperglycemia over time. No subject with CFRD without fasting hyperglycemia had retinopathy or abnormal U(alb:Cr). In CFRD subjects with fasting hyperglycemia and diabetes for > or = 10 years, 14% had microalbuminuria and 16% had retinopathy. Autonomic neuropathy and gastrointestinal symptoms each were seen in 52% and somatic abnormalities in 22% of patients with or without fasting hyperglycemia.

CONCLUSIONS

Diabetic microvascular complications occur in CFRD, although the prevalence of retinopathy and nephropathy appears to be less than that found in other forms of diabetes. Annual complication screening should occur after known diabetes duration of 5 years in patients with CFRD with fasting hyperglycemia.

Cystic fibrosis-related diabetes: the presence of microvascular diabetes complications

OBJECTIVE

Cystic fibrosis (CF)-related diabetes has been regarded as a mild form of diabetes with a low risk of severe diabetes complications. The prevalence of CF-related diabetes increases with age, resulting in a 50% prevalence of diabetes at age 30 years. We sought to investigate whether microvascular complications in CF-related diabetes appear with a relevant frequency.

RESEARCH DESIGN AND METHODS

Thirty-eight patients aged 30 (range 18-55) years with CF-related diabetes for 20 (0-31) years were screened for diabetes complications. Because of chronic pulmonary infections, the majority of patients were regularly treated with aminoglycoside and cyclosporine given frequently.

RESULTS

Since the pharmacological treatment of lung transplant patients could influence metabolical regulation and renal function, the results are given separately for nontransplanted (n = 29) and transplanted (n = 9) CF patients. Nine patients (27%) had retinopathy, two of which had proliferative retinopathy and needed laser treatment. Lung transplantation did not affect the prevalence of retinopathy. In nontransplanted patients, nine had hypertension, three microalbuminuria, and one elevated creatinine. None had macroalbuminuria. In transplanted patients, eight of nine had hypertension, two had microalbuminuria, and none had macroalbuminuria. Seven of nine lung transplant patients had elevated plasma creatinine, and severely reduced glomerular filtration rate was significantly more frequent.

CONCLUSIONS

A high frequency of diabetic retinopathy was found in patients with insulin-treated CF-related diabetes, stressing the need for a regular screening program as in type 1 diabetes. Severely impaired kidney function was common in lung transplant patients, probably secondary to cyclosporine treatment.