Symmetric dimethylarginine in hyperthyroid cats before and after treatment with radioactive iodine.

OBJECTIVES: The purpose of this study was to evaluate symmetric dimethylarginine (SDMA) in hyperthyroid cats before and after treatment with radioactive iodine and to determine how pretreatment SDMA relates to the development of post-treatment azotemia. METHODS: Eighty-four non-azotemic hyperthyroid cats had serum SDMA and creatinine evaluated before and 1, 3 and 6 months after treatment with radioiodine therapy. RESULTS: Baseline SDMA was increased in 7% (n = 6/84) of cats, whereas SDMA was increased in 19% (n = 15/81), 20% (n = 16/80) and 32% (n = 26/81) at 1 month, 3 months and 6 months after treatment, respectively. Creatinine was not elevated in any of the cats at baseline because of the study design, and was elevated in 6% (n = 5/81), 15% (n = 12/80) and 15% (n = 12/81) of cats at 1, 3 and 6 months after treatment, respectively. SDMA (median 11 µg/dl, range 1-22 µg/dl) was significantly higher at 3 (12 µg/dl, range 6-45 µg/dl; P = 0.005) and 6 months (11 µg/dl, 6-25 µg/dl; P <0.001) compared with baseline (11 µg /dl, range 1-21 µg/dl). The median baseline SDMA was significantly higher in the azotemic group (13 µg/dl, range 11-22 µg/dl) compared with the non-azotemic group (10 µg/dl, range 1-21 µg/dl, P = 0.002). The sensitivity of SDMA for detecting azotemia after treatment was 15.4%, with a specificity of 94.4%. Baseline serum SDMA concentration had a moderately positive association with baseline creatinine concentration (P <0.001, r = 0.437). At 6 months, there was a strong positive correlation between SDMA and creatinine concentrations (P <0.001, r = 0.721). There was no significant correlation with SDMA and thyroxine at baseline (P = 0.772, r = -0.034) or 6 months (P = 0.492, r = -0.078). CONCLUSIONS AND RELEVANCE: SDMA increases in cats treated for hyperthyroidism with radioactive iodine and likely reflects associated changes in glomerular filtration rate. An increased SDMA concentration above the reference interval prior to treatment has a high specificity but poor sensitivity for the prediction of post-treatment azotemia.

Osmotic stress and mortality in elderly patients with kidney failure: a retrospective study.

PURPOSE: Water balance disorders are associated with a high risk of death in elderly patients. The role of osmotic stress intensity and its direction toward hypo- or hypernatremia is a matter of controversy regarding patients' survival. The aims of this study were, first, to measure the frequency of cellular hydration disorders in patients over 75 years old hospitalized in nephrology department for reversible acute renal failure, and second, to compare the impact of hyperhydration and hypohydration on the risk of death at 6 months. PATIENTS AND METHODS: We retrospectively studied the data of 279 patients with chronic kidney disease (CKD), aged 75 years or older, with pre-renal azotemia who experienced dysnatremia. We classified them according to natremia levels and compared their outcome in univariate and multivariate analysis. RESULTS: The patients were on average 83.2±5.4 years old. Among them, 128 were normonatremic, 82 were hyponatremic and 69 were hypernatremic. Osmotic stress intensity appreciated by the variation rate of natremia did not differ significantly between hyper- and hyponatremic patients. Patients had CKD stage 3B and 4 with acute kidney injury (AKI) of different severities. We observed that only hypernatremia was linked to death in the first 6 months following hospital discharge. CONCLUSION: Hypernatremia is a strong predictor of fatal outcome in elderly patients suffering from chronic kidney impairment and referred for pre-renal azotemia.

Association between decreased blood pressure and azotaemia in canine babesiosis.

Acute tubular necrosis (ATN) was described in canine babesiosis. Hypotension is considered as one of the factors which influence the development of hypoxic renal damage. In this study hypotension defined as mean arterial pressure (MAP) < 80 mmHg was detected in 7 out of 48 dogs (14.6%) infected with Babesia canis. Lower systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and MAP were detected in azotaemic dogs infected with B. canis. Statistically significant negative correlations between blood pressures (SAP, DAP and MAP) and serum creatinine and urea concentrations showed the influence of decreased blood pressure on the development of azotaemia and is probably also associated with ATN in canine babesiosis.

Elevated blood urea nitrogen and medical outcome of psychiatric inpatients.

Elevated blood urea nitrogen (BUN) is associated with increased severity of illness and mortality, but its predictive value has not been studied in patients admitted to free-standing psychiatric hospitals. To determine the clinical outcome of psychiatric inpatients with elevated BUN on admission and to create a quantitative method of using BUN for predicting deteriorations requiring transfers of psychiatric inpatients to a general hospital we conducted a retrospective cohort study of 939 adults consecutively admitted to a free-standing psychiatric hospital in 2010. Transfer to a general hospital was used as a proxy marker for poor medical outcome. The score Age (years) plus BUN (mg/dL) was used in sensitivity analyses to identify patients with medical deterioration in derivation (N = 523) and validation (N = 414) samples. Fifty-two (5.5%) patients had admission azotemia (BUN >25 mg/dL). Medical deteriorations requiring emergency transfer to a general hospital occurred in 24 (46.2%; 95% confidence interval = 32.6-49.8%) of azotemic patients and 112 (12.6%; 95% confidence interval = 10.4-14.8%) of those with normal BUN (p < 0.0001). Age + BUN ≥ 90 identified 51 transferred patients and had positive and negative predictive values of 39.8 and 89.5%, respectively, in the entire sample. We conclude that psychiatric inpatients with BUN >25 mg/dL or Age + BUN ≥ 90 are at risk for medical deterioration. Free-standing psychiatric hospitals should develop models of care requiring frequent, scheduled medical follow-up and enhanced monitoring for this vulnerable populations.

Albuminuria and its correlates in type 2 diabetic patients.

INTRODUCTION: The aim of this study was to determine the prevalence of albuminuria and its correlates and investigate disease management for patients with type 2 diabetes mellitus in Ahvaz. MATERIALS AND METHODS: This was a cross-sectional study on the 350 patients with type 2 diabetes mellitus attending the Diabetes Clinic at Golestan Hospital, from October 2010 to September 2011. Demographic characteristics were recorded and height, weight, and blood pressure were measured. Blood urea nitrogen and serum levels of creatinine, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, and glycosylated hemoglobin A were measured in fasting blood samples. Spot urine and 24-hour urine collection were tested for albumin and kidney ultrasonography was done. RESULTS: A total of 72 of 350 patients (20.6%) had microalbuminuria and 18 (5.1%) had macroalbuminuria. Elevated serum creatinine was seen in 6.9% and azotemia in 6.0%. In multivariable analysis, blood urea nitrogen level, glycosylated hemoglobin A, and duration of diabetes mellitus were associated with urinary albumin excretion (P = .04). A small proportion of the participants achieved optimal treatment goals for modifiable risk factors. CONCLUSIONS: Abnormal urinary albumin excretion is seen in one-quarter of type 2 diabetic patients and a small but important number of them have azotemia. Albuminuria was found to be associated with long-term duration of diabetes mellitus, poor glucose control (revealed by high glycosylated hemoglobin A levels), and high blood urea nitrogen. Poor glycemic control may have a significant role in the progression of diabetic nephropathy in these patients.

Fractional excretion of uric acid as a predictor for saline responsiveness in long-term kidney transplant patients.

BACKGROUND/AIMS: Subclinical hypovolemia may contribute to allograft dysfunction in long-term kidney transplant (KT) patients. In order to predict responsiveness to saline hydration, indices for tubular transport were investigated. METHODS: Fifty-four clinically euvolemic long-term KT patients with recently aggravated azotemia were given intravenous hydration as follows: 0.9% saline 5 ml/kg over 1 h, followed by 0.9% saline 1 ml/kg/h over 12 h and 1 liter of 0.45% saline over the next 24 h. Serum and urine data were collected and analyzed to assess responses. RESULTS: In all patients, saline hydration relieved azotemia, as shown by blood urea nitrogen (46.9 ± 17.2 vs. 39.3 ± 15.4 mg/dl; p < 0.01) and serum creatinine levels (2.9 ± 1.1 vs. 2.5 ± 1.1 mg/dl; p < 0.01) on day 0 versus day 2. In 38 patients, serum creatinine did not increase in the following month (70% responders). Compared with the nonresponders, the responders had a higher urine-to-plasma creatinine ratio and lower fractional excretion of sodium, uric acid and urea at admission. Multivariate logistic regression analysis revealed that responsiveness to saline hydration was independently associated with lower fractional excretion of uric acid. CONCLUSION: Subclinical hypovolemia should be considered in long-term KT patients with azotemia of unexplainable causes. Fractional excretion of uric acid may predict responsiveness to saline hydration.

Acute oxalate intoxication associated to ingestion of eshnan (Seidlitzia rosmarinus) in sheep.

An outbreak of acute oxalate intoxication in a sheep flock was associated to Seidlitzia rosmarinus (Chenopodiaceae) with a mortality rate of about 19%. Affected sheep showed marked azotemia and hypocalcemia. Post-mortem findings included congestion and hemorrhage in visceral organs, ruminitis frequently associated with precipitation of birefringent calcium oxalate crystals, and acute nephrosis with numerous birefringent calcium oxalate crystals in renal tubules. This is the first report of oxalate poisoning due to ingestion of S. rosmarinus in sheep.

Association between chronic azotemic kidney disease and the severity of periodontal disease in dogs.

Naturally occurring periodontal disease affects >75% of dogs and has been associated with cardiac lesions and presumptive endocarditis. However, the relationships between periodontal disease and chronic kidney disease (CKD) in dogs have not been studied. In a retrospective longitudinal study the incidence of azotemic CKD was compared between a cohort of 164,706 dogs with periodontal disease and a cohort of age-matched dogs with no periodontal disease from a national primary care practice. These dogs contributed 415,971 dog-years of follow-up from 2002 to 2008. Hazard ratios and 95% confidence intervals from Cox regression were used to compare the incidence of azotemic CKD in dogs with stage 1, 2, or 3/4 periodontal disease to dogs with no periodontal disease. The hazard ratio for azotemic CKD increased with increasing severity of periodontal disease (stage 1 hazard ratio=1.8, 95% confidence interval: 1.6, 2.1; stage 2 hazard ratio=2.0, 95% confidence interval: 1.7, 2.3; stage 3/4 hazard ratio=2.7, 95% confidence interval: 2.3, 3.0; P(trend)=<0.0001) after adjustment for age, gender, neuter status, breed, body weight, number of hospital visits, and dental procedures. Increasing severity of periodontal disease was also associated with serum creatinine >1.4 mg/dl and blood urea nitrogen >36 mg/dl, independent of a veterinarian's clinical diagnosis of CKD.

Prerenal azotemia in congestive heart failure.

Prerenal failure is used to designate a reversible form of acute renal dysfunction. However, the terminology encompasses different conditions that vary considerably. The Acute Kidney Injury Network group has recently standardized the acute kidney injury (AKI) definition and classification system; however, these criteria have not determined specific diagnostic criteria to classify prerenal conditions. The difference in the pathophysiology and manifestations of prerenal failure suggests that our current approach needs to be revaluated. Several mechanisms are recognized as contributory to development of a prerenal state associated with cardiac failure. Because of the broad differences in patients' reserve capacity and functional status, prerenal states may be triggered at different time points during the course of the disease. Prerenal state needs to be classified depending on the underlying capacity for compensation, the nature, timing of the insult and the adaptation to chronic comorbidities. Current diagnosis of prerenal conditions is relatively insensitive and would benefit from additional research to define and classify the condition. Identification of high-risk states and high-risk processes associated with the use of new biomarkers for AKI will provide new tools to distinguish between the prerenal and established AKI. Achieving a consensus definition for prerenal syndrome will allow physicians to describe treatments and interventions as well as conduct and compare epidemiological studies in order to better describe the implications of this syndrome.

Azotemia in cats with feline hypertrophic cardiomyopathy: prevalence and relationships with echocardiographic variables.

OBJECTIVES: The prevalence of renal azotemia in cats with acquired heart disease is not well documented. The aims of this study were therefore (1) to determine the prevalence of azotemia within a hospital population of cats with hypertrophic cardiomyopathy (HCM), and (2) to evaluate the relationship between echocardiographic variables and plasma urea and creatinine. ANIMALS, MATERIALS AND METHODS: 134 client-owned cats were retrospectively studied including 102 cats with HCM and 32 control cats. A complete physical examination, electrocardiography, systolic arterial blood pressure measurement, thoracic radiographs, and echocardiography were performed. Plasma creatinine and urea were determined in all cats. The animal was considered azotemic if plasma creatinine was >1.8 mg/dL and/or urea >65 mg/dL (i.e. BUN> 30 mg/dL). RESULTS: The prevalence of azotemia was lower in control cats (25.0%) than in cats with HCM (58.8%) (P=0.003). No significant differences in plasma urea and creatinine were observed between the HCM and control cats. There was no effect of plasma creatinine and urea on conventional echocardiographic variables in cats with HCM. CONCLUSIONS: Azotemia is a frequent finding in cats with HCM but is not dependent on echocardiographic variables.

An investigation of predictors of renal insufficiency following treatment of hyperthyroidism in cats.

To determine if routine pre-treatment clinical data can be used to predict the development of overt renal insufficiency following treatment of feline hyperthyroidism, we studied retrospectively all non-azotemic cats undergoing treatment for hyperthyroidism at our hospital. Medical records were reviewed for signalment, clinical signs, and serum biochemical, hematologic and urinalysis parameters before and after treatment for hyperthyroidism. Two groups - cats that developed post-treatment renal insufficiency, and those that did not - were compared. No significant differences could be detected between the groups with respect to the parameters measured. Our study suggests that the results of routine pre-treatment clinical data cannot be used to reliably predict renal function after treatment for hyperthyroidism, validating the necessity of a methimazole trial prior to definitive therapy. The widely held belief that cats with pre-treatment urine specific gravity>1.035 are at less risk for development of renal azotemia after treatment of hyperthyroidism seems unwarranted.

Azotemia in cancer patients during inpatient rehabilitation.

This paper presents a study of the relationship between prerenal azotemia and rehabilitation outcomes of cancer patients. A retrospective chart review of 70 patients who underwent inpatient rehabilitation in a tertiary cancer center was undertaken. Eight patients with creatinine values >1.5 were excluded. The remaining 62 patients were divided into 2 groups according to the blood urea nitrogen/creatinine (BUN/Cr) ratio: 27 (44%) in the prerenal azotemia group (BUN/Cr > or = 20) and 35 (56%) in the non-azotemic group (BUN/Cr < 20). Age, gender, <10 g/dL of hemoglobin, co-morbidity (diabetes mellitus and/or hypertension), discharge destiny and median rehabilitation length of stay were not significantly different in these 2 groups. Prerenal azotemia was present in a significant number of cancer patients, but it did not impact the length of rehabilitation stay or discharge destiny.

Safety of gadodiamide mixed with a small quantity of iohexol in patients with impaired renal function undergoing coronary angiography.

Gadolinium-based contrast agents can be used in diagnostic and interventional angiography, and are safe in recommended doses in patients with impaired renal function, but the image quality is usually unsatisfactory. The objective of the present study is to evaluate the safety of gadolinium mixed with a small quantity of iodine-based contrast agent and the image quality of this mixture in patients with renal insufficiency undergoing diagnostic coronary angiography. Forty-two patients with baseline creatinine level>1.5 mg/dl were randomized into gadolinium or iodine groups. In the gadolinium group gadodiamide was mixed with 1:3 iohexole and in the iodine group only this agent was used as contrast material. Peak creatinine levels 48-72 h after the procedure were measured. The primary end point was the development of contrast-induced nephropathy (CIN), defined as >25% increase of baseline creatinine levels, and the secondary end points were absolute and relative changes in baseline creatinine levels. Total contrast volumes used were not different between groups (57+/-11 ml in gadolinium and 55+/-10 ml in iodine; P=0.68). Mean creatinine level did not increase significantly in the gadolinium group (from 1.9+/-0.3 to 1.9+/-0.4 mg/dl; P=0.06), but did in the iodine group (from 2.0+/-0.4 to 2.3+/-0.5 mg/dl; P=0.001). No patient had CIN in the gadolinium group whereas 5 (23%) patients had this phenomenon in the iodine group (P=0.048). Contrast regimen was very well tolerated in the gadolinium group, with only transient headache in two patients. Gadodiamide mixed with a small quantity of iohexol is safe in patients with azotemia undergoing diagnostic coronary angiography. The image qualities obtained with this combination are also satisfactory in all of the cases. Further evaluation of the safety of this technique is warranted, especially in other types of diagnostic and interventional procedures in which a higher amount of contrast dye is needed.