Follow-up of GFR estimated from plasma creatinine after cimetidine administration in patients with diabetes mellitus type 2.

BACKGROUND: The glomerular filtration rate (GFR) can be estimated from plasma creatinine according to the formula of Cockcroft and Gault (CG). When tubular secretion of creatinine is inhibited by cimetidine the mean difference between the Cockcroft-Gault clearance (CG(Cim) and GFR approximates zero, but there is still some interindividual difference, especially in type-2-diabetic patients. We studied during longitudinal follow-up, whether the discrepancies between CG(Cim) and GFR per patient are consistent in time in type-2-diabetic patients. PATIENTS AND METHODS: In 1996 and 1998 (interval 20-26 months) GFR was measured in 21 patients as the urinary clearance of continuously infused 125I-iothalamate. Plasma creatinine was analyzed with an enzymatic assay before and after oral cimetidine 800 mg t.i.d. during 24 hours. GFR estimations were calculated with the Cockcroft-Gault formula before (CG) and after cimetidine (CG(Cim)) and expressed as means +/- SEM. RESULTS: GFR deteriorated from 89.7 +/- 5.7 to 81.3 + 5.8 ml/min/1.73 m2 and CG(Cim) from 85.3 +/- 5.7 to 81.1 +/- 6.6 ml/min/1.73 m2, whereas CG decreased from 102.4 +/- 6.8 to 98.4 +/- 7.0 ml/min/1.73 m2. Changes in GFR and changes in CG(Cim) were correlated (r = 0.72, p < 0.001) and were not significantly different from each other. The discrepancy between CG(Cim) and GFR per patient in 1996 also correlated with the discrepancy between CG(Cim) and GFR in 1998 (r = 0.85, p < 0.001 ). CONCLUSIONS: In individual patients the discrepancies between the CG(Cim) and GFR are consistent in time and the change in GFR is reflected by the change in CG(Cim). This small variability means that CG(Cim), based on an enzymatic plasma creatinine assay, would be suitable for follow-up of GFR in type-2-diabetic patients, independent of albuminuria.

Fasting and post-methionine homocysteine levels in NIDDM. Determinants and correlations with retinopathy, albuminuria, and cardiovascular disease.

OBJECTIVE: The increased cardiovascular risk in subjects with NIDDM is partly explained by an association with established risk factors like hypertension, dyslipidemia, and obesity. Mild hyperhomocysteinemia has emerged as a new risk factor for cardiovascular disease. The purpose of this study was to assess its role in NIDDM. RESEARCH DESIGN AND METHODS: We studied predictors of homocysteine levels and correlations between homocysteine and (micro-)albuminuria, retinopathy, and history of cardiovascular disease in normotensive NIDDM subjects under stable metabolic control. This was done in 85 NIDDM subjects by measuring fasting and post-methionine-loading homocysteine levels together with blood pressure, BMI, serum cholesterol, triglyceride, HDL cholesterol, folate, vitamin B12, pyridoxal-5-phosphate, HbA1c, and (micro-)albuminuria and creatinine clearance in triplicate 24-h urine samples. The relationship between micro- and macrovascular complications and fasting homocysteine only was studied in an additional 65 subjects, giving a total of 150 subjects. RESULTS: In multiple regression analysis, significant (P < 0.05) predictors of fasting homocysteine were low-normal values of creatinine clearance (threshold effect at < 80 ml.min-1 .1.73 m-2), folate (< 20 nmol/l), and vitamin B12 (< 350 pmol/l), and postmenopausal status in women. Determinants of post-methionine homocysteine were pyridoxal-5-phosphate levels < 80 nmol/l, creatinine clearance, and sex (higher levels in women). Hyperhomocysteinemia did not cluster with other cardiovascular risk factors, like hypertension, obesity, or dyslipidemia. Regarding cardiovascular complications, fasting homocysteine, but not post-methionine homocysteine, was higher in subjects with a history of cardiovascular disease. There was a stepwise increase in the prevalence of subjects with cardiovascular disease with increasing fasting homocysteine. The prevalence of cardiovascular disease was 19.4% in the bottom quartile of fasting homocysteine, versus 55.0% in the top quartile (P for trend < 0.01). Neither fasting homocysteine nor post-methionine homocysteine correlated with (micro-)albuminuria or with retinopathy. CONCLUSIONS: The findings suggest that homocysteine levels in NIDDM rise even with modest deterioration of renal function and when vitamin status is in the low to low-normal range. Fasting homocysteine correlates with macrovascular disease, but we found no evidence of a correlation with retinopathy or (micro-)albuminuria. Post-methionine homocysteine levels do not show a correlation with micro- or macrovascular complications.

Glomerular filtration rate estimation from plasma creatinine after inhibition of tubular secretion: relevance of the creatinine assay.

BACKGROUND: Estimation of glomerular filtration rate (GFR) from plasma creatinine concentration after inhibition of tubular creatinine secretion with cimetidine provides a good assessment in patients with various nephropathies and with non-insulin-dependent diabetes mellitus (NIDDM). The aim of this study was to compare cimetidine-aided GFR estimations using various creatinine assays. METHODS: In 30 outpatients with NIDDM GFR was measured as the urinary clearance of continuously infused [125I]iothalamate. Plasma creatinine concentration was analysed after oral cimetidine with an alkaline picrate (AP) method, with an enzymatic (PAP) assay and with HPLC. GFR estimations were calculated with the Cockcroft Gault formula (CG). RESULTS: AP creatinine concentrations were significantly higher than PAP or HPLC values. GFR estimations by AP (CG(AP) 66 +/- 19 ml/min/1.73 m2, mean SD) were significantly lower than GFR (89 +/- 30), whereas CG(PAP) (85 +/- 30) and CG(HPLC) (84 +/- 34 ml/min/1.73 m2) were not. Bland and Altman analysis showed a difference between CG(AP) and GFR of -22.4 +/- 17.7 ml/min/1.73 m2; this difference becomes larger when the GFR increases. The difference between CG and GFR was only -3.8 +/- 14.8 ml/min/1.73 m2 for PAP and -4.4 +/- 17.5 ml/min/1.73 m2 for HPLC, without any systematic difference. CONCLUSION: A good assessment of the GFR from plasma creatinine after cimetidine administration is possible when creatinine is measured with an enzymatic assay or with the less convenient HPLC method. The more widespread and cheaper alkaline picrate assay is not suitable for GFR-estimation.

Short-term variability and sampling distribution of various parameters of urinary albumin excretion in patients with non-insulin-dependent diabetes mellitus.

We determined the degree of variability and sampling distribution of several commonly used parameters of microalbuminuria in patients with non-insulin-dependent diabetes mellitus (NIDDM) and proposed a sampling strategy for estimating the level of albuminuria. Four patients with NIDDM with previously documented microalbuminuria collected 30 consecutive split (overnight and daytime) 24-hour urine samples (experiment A). These samples were analyzed for total 24-hour albumin excretion; daytime, overnight, and 24-hour albumin concentration; and daytime, overnight, and 24-hour albumin-to-creatinine ratio. In a second experiment (B), 10 patients collected 10 consecutive overnight urine samples. Finally, a total of 300 separate triplicate urine samples were analyzed for the variability of 24-hour albumin excretion (100 samples) and albumin-to-creatinine ratios in 24-hour urine (100 samples) and overnight urine (100 samples). We found that the sampling distribution shape of all parameters of albuminuria is positively skewed, without consistent evidence of log-normality. When two methods were used for quantifying day-to-day variability (the interquartile range/median ratio and the chance of a single measurement being >50% off the actual value of albuminuria), the overnight albumin-to-creatinine ratio is the least-variable parameter of albuminuria, scoring 0.38% and 10% on both methods, respectively, in experiment A. Collecting multiple samples of overnight urine improves accuracy. The largest gain in precision in estimating the actual value of albuminuria is obtained for sample sizes of three and five and does not increase with nonconsecutive sampling of urine. Based on the combined data from experiments A and B, the expected mean deviation of the median of three and five overnight samples from the actual level of the overnight albumin-creatinine ratio is 17.9% and 12.1%, respectively. An analysis of variability in three sets of 100 triplicate 24-hour urine samples shows that the overnight albumin-to-creatinine ratio is a significantly more-constant parameter of microalbuminuria than the amount of albumin excreted in 24 hours or the albumin-to-creatinine ratio in 24-hour urine (p < 0.05). We concluded that the parameters of diabetic albuminuria have positively skewed, non-log-normal sampling distributions. The overnight albumin-to-creatinine ratio is the least-variable parameter of microalbuminuria. We recommend collecting three consecutive early morning urine samples, using the median value of the albumin-to-creatinine ratio in these samples for quantifying albuminuria.

Estimation of the glomerular filtration rate in NIDDM patients from plasma creatinine concentration after cimetidine administration.

OBJECTIVE: Glomerular filtration rate (GFR) can be estimated in patients with renal disease from plasma creatinine concentration, age, sex, and body weight according to the formula of Cockcroft and Gault. The hypothesis that this method can be improved when tubular secretion of creatinine is inhibited by cimetidine was studied in NIDDM patients. RESEARCH DESIGN AND METHODS: In 30 outpatients with NIDDM and normo- (n = 10), micro- (n = 9), or macroalbuminuria (n = 11), GFR was measured as the urinary clearance during continuous infusion of 125I-labeled iothalamate. Plasma creatinine concentration was analyzed with an enzymatic assay before and after 800 mg t.i.d. oral cimetidine was given during a 24-h period. RESULTS: Plasma creatinine rose in all patients after cimetidine administration and, as a consequence, the clearance calculated with the Cockcroft-Gault formula fell. The ratio of this formula and GFR decreased from 1.16 +/- 0.20 to 0.97 +/- 0.16 (means +/- SD). This ratio tended to be smaller in the normo- (0.93) than in the micro- (0.98) and macroalbuminuric (1.00) groups. Also, 20 patients with a BMI < 30 kg/m2 had a smaller ratio than those with a BMI > 30 kg/m2 (0.92 vs. 1.07; P < 0.05). Bland and Altman analysis showed a difference of the Cockcroft-Gault formula and GFR of 12.0 +/- 17.4 ml.min-1 (1.73 m2)-1, which decreased to -3.8 +/- 14.8 ml.min-1.(1.73 m2)-1. The same analysis of 24-h creatinine clearance with urine collection and GFR showed larger standard deviations. CONCLUSIONS: GFR can be estimated in an acceptable way from plasma creatinine concentration after cimetidine administration in outpatients with NIDDM. Despite a nonsignificant underestimation in normoalbuminuric and overestimation in overweighted patients, this method is superior to 24-h creatinine clearance with outpatient urine collection.

Determinants of progression of microalbuminuria in patients with NIDDM.A prospective study.

OBJECTIVE: To assess the degree of interindividual variation in the rate of progression of microalbuminuria and to identify determinants of progression of microalbuminuria in patients with NIDDM. RESEARCH DESIGN AND METHODS: In a prospective cohort study, 58 microalbuminuric NIDDM patients were followed for a period of at least 24 months. During this period, the level of microalbuminuria in these patients was assessed in triplicate 24-h urine samples on at least four separate visits. All patients had stable metabolic control and controlled blood pressure during follow-up. Microalbuminuria was defined as an albumin-to-creatinine ratio in 24-h urine of between 3 and 30 mg/mmol. The individual rates of progression of microalbuminuria were calculated from linear regression analysis. At baseline, the following data were collected for all patients: age, sex, ethnicity, time since diagnosis of NIDDM, smoking habits, drug use, blood pressure, BMI, HbA1c, serum creatinine, cholesterol, triglyceride, and HDL cholesterol concentrations. RESULTS: Microalbuminuria was found to progress linearly in time. Considerable differences in rates of progression of microalbuminuria were found, the absolute yearly change in albumin-to-creatinine ratio ranging from -5.2 to 12.9 mg/mmol. In bivariate analyses, serum triglyceride concentration, use of ACE inhibitors, mean arterial blood pressure, HDL cholesterol, and time since diagnosis of NIDDM correlated with progression of microalbuminuria (P < or = 0.05). In stepwise multiple regression analysis, a high triglyceride-to-HDL cholesterol ratio at baseline (P = 0.006) and the use of ACE inhibitors (P = 0.007) were identified as the only independent predictors of progression of microalbuminuria. CONCLUSIONS: The rate of progression of microalbuminuria in NIDDM differs considerably between subjects. Diabetic dyslipidemia (high serum triglyceride and low HDL cholesterol) is a predictor of more rapid progression of microalbuminuria in patients with well-controlled blood pressure.

Vascular complications in relation to ethnicity in non-insulin-dependent diabetes mellitus.

The purpose of this study was to investigate the effect of ethnicity on the development of diabetic retinopathy and nephropathy as markers for microvascular complications and of angina pectoris as a marker for macrovascular complications. We evaluated data from 1124 patients with non-insulin-dependent diabetes mellitus (NIDDM) of Caucasian, Mongoloid, Asian, Armenian, Northern African and Negroid origin who were referred between January 1993 and December 1994. Logistic regression analyses showed that the occurrence of microvascular complications was significantly associated with duration of NIDDM. In addition, retinopathy was significantly associated with glycated haemoglobin A1c (HbA1c) and nephropathy with triglycerides (P < 0.05 and P < < 0.001 respectively). Northern African origin was associated with retinopathy (P < 0.05) and Asian origin with nephropathy (P < 0.005). Macrovascular complication was associated with age and triglyceride level (P < 0.001 and P < 0.05 respectively). Northern African and Negroid ethnicity exclusively did not show a gradual increase in the risk for angina pectoris with increasing age. Moreover, a negative association between Northern African as well as Negroid ethnicity and macrovascular complication was observed (P = 0.05 and P < 0.05 respectively). In support of these observations, we found a favourable lipid profile in both mentioned groups. In summary, we have shown that, in patients with NIDDM, ethnicity is associated with macrovascular complications and duration of the disease with microvascular complications.

Can reduction in hypertriglyceridaemia slow progression of microalbuminuria in patients with non-insulin-dependent diabetes mellitus?

The objective of this study was to investigate whether reduction in hypertriglyceridaemia is associated with a slower rate of progression of microalbuminuria in patients with non-insulin-dependent diabetes mellitus (NIDDM). Fifteen normotensive NIDDM patients with hypertriglyceridaemia (> 2.5 mmol L-1) and microalbuminuria were randomly selected to receive either placebo (eight patients) or gemfibrozil 600 mg b.i.d. (seven patients). Progression of microalbuminuria was assessed during a 12-month follow-up period with measurements, consisting of blood tests and triplicate 24-h urine collections, at 1, 3, 6, 9 and 12 months. All but one patient in the treatment group showed a favourable response (> or = 20% reduction) of hypertriglyceridaemia to gemfibrozil. One patient in the placebo group showed a spontaneous reduction in triglyceride levels. Progression of microalbuminuria was lower, although not statistically significantly so, in the treatment group (36%) than in the placebo group (65%). In the group with > or = 20% reduction in triglyceride levels, progression of MA was significantly lower than in the group with stable or increasing triglyceride levels (+1%, range -56% to +49% vs. +97%, range -35% to +202% respectively) (P = 0.03). Continued follow-up data of patients switching from placebo to gemfibrozil after the trial further support the role of serum triglyceride reduction in stabilizing albumin excretion. In conclusion, the results indicate that, in microalbuminuric NIDDM patients, effective treatment of dyslipidaemia could be associated with stabilization of urinary albumin excretion.

Renal tubular acidosis. Pathophysiology and diagnosis.

The pathophysiology of renal tubular acidosis is slowly being unraveled, which has implications for the traditional classification of the condition. Nonetheless, the diagnosis of renal tubular acidosis is still easy to establish, and identification of the specific pathophysiological subtype is relatively straightforward. The diagnostic information required usually includes only urinary pH and sodium, potassium, and chloride concentrations and serum potassium level. The urinary pH is not a diagnostic test for renal tubular acidosis, but it serves to distinguish between the various subtypes.

Hypovitaminosis D in immigrant women: slow to be diagnosed.

Hypovitaminosis D osteopathy should be considered in immigrant women with musculoskeletal pain.

Malacoplakia. Two case reports and a comparison of treatment modalities based on a literature review.

Malacoplakia is a rare infectious disease that has been almost exclusi vely reported in urology and pathology journals. We studied two cases of malacoplakia that were primarily referred to the department of internal medicine because of fever and abdominal masses. In one patient, malacoplakia was diagnosed in the unusual ovarian location, while in the other patient a large renal mass was found and ciprofloxacin therapy failed because of bacterial resistance. The clinical and radiologic appearance of malacoplakia often mimics that of a malignant tumor. The principal disorder is probably a monocytic-macrophagic bactericidal defect. A definitive diagnosis depends on microscopic detection of Michaelis-Gutmann bodies by means of von Kossa stain. We outlined treatment strategies on the basis of a review of the literature since 1981, which included 140 cases. If possible, immunosuppressive drugs should be stopped. Quinolone antibiotic treatment and surgical excision or incision and drainage lead to the highest cure rates (90% and 81%, respectively). Specific intracellular penetration of quinolone antibiotics is a possible reason for the higher cure rate achieved with these antibiotics. Bethanechol has been suggested to correct the supposed fundamental disturbance by increasing the intrecellular cyclic guanosine monophosphate concentration, but there is still no convincing evidence of its clinical efficacy.

A simple method for the quantification of portosystemic shunting (PSS) in patients with portal hypertension.

Portosystemic shunting (PSS) was evaluated in 32 patients with chronic liver disease by the rectal administration of iodine-123 I-amphetamine (IMP method), a radionuclide which is rapidly absorbed from the sigmoid and extracted by liver and lungs. Simultaneous measurement of pulmonary and hepatic uptake supplies a shunt fraction (SF) as an index of PSS. The IMP method was compared with the ammonia tolerance test (NH3TT), and there proved to be a significant correlation between these two methods (r = 0.75, p < 0.001). Assuming that an increase of > 7 mumol/l in arterial ammonia concentration after NH3TT represents PSS, the IMP method had a sensitivity of 0.93. When fasting (NH3) was > 50 mumol/l, all patients showed pathological PSS with either method, but this was also the case in 50% of patients with normal basal arterial ammonia. There was also a significant correlation between the IMP method and the Child-Pugh classification (r = 0.75, p < 0.001). Endoscopy in 28 patients revealed absence of varices in 11, of whom, however, 7 (64%) had an increased SF and although all 15 patients with ascites had increased SF, this was also the case in 12 of the 17 patients without ascites. In conclusion, PSS evaluation using IMP is a non-invasive, sensitive method without patient discomfort which might be used in the staging and follow-up of chronic liver disease.

Effect of antihypertensive drugs on insulin absorption.

OBJECTIVE: To examine the effects of antihypertensive drugs on the absorption of subcutaneously injected insulin. RESEARCH DESIGN AND METHODS: Eleven healthy volunteers (group 1) were given 1 mg/kg body wt propranolol three times a day during 48 h and a single dose on the morning of investigation. Seven other healthy volunteers (group 2) were given 10 mg nifedipine 30 min before subcutaneous injection of 10 U 125I-labeled soluble insulin. Absorption was measured by counting radioactivity externally. In both groups, control experiments were conducted under the same conditions without administration of propranolol or nifedipine. RESULTS: Propranolol usage was associated with higher mean percentages of remaining activity (P less than 0.05 by analysis of variance [ANOVA]) than in the control experiment. In the nifedipine experiment, mean percentages were significantly lower compared with the control experiment (P less than 0.02 by ANOVA). The mean decline in activity of all 30-min periods was 6.8 +/- 3.5 vs. 3.6 +/- 3.7% for control versus propranolol (group 1) (P less than 0.05) and 6.3 +/- 1.8 vs. 9.6 +/- 3.2% for control versus nifedipine (group 2) (NS). CONCLUSIONS: Antihypertensive drugs can influence insulin absorption. Propranolol (a peripheral vasoconstrictor) decreases insulin absorption, whereas nifedipine (a vasodilatator) increases insulin absorption.

The relationship between densitometry of the radius and vertebral fractures.

In 105 postmenopausal women with clinical suspicion of osteoporosis single photon absorptiometry (SPA) of the forearm and fracture percentage of the thoracic and lumbar spine were estimated. SPA was performed on the commonly used mid-radius site as well as on a modified distal radius site where radius and ulna are separated by five mm. Spine fracture percentage was inversely correlated with mid-radius SPA (r = -0.49) but more closely with distal radius SPA (r = -0.61). With bone mineral density values above 0.400 g/cm2 on the distal radius, no fractures were found. Between 0.325 and 0.400 g/cm2, 35% of the patients showed vertebral fractures but only up to a maximum of 30%. Below 0.325 g/cm2, 89% of the women had crushed vertebrae, often more than 30% of those measured. In conclusion, these results indicate that modified distal radius densitometry is superior to the commonly used mid-radius measurement and has some predictive value for the presence of vertebral fractures.

Acute pancreatitis in a case of Werner's syndrome with severe hyperlipidaemia.

A patient with Werner's syndrome and acute pancreatitis due to severe hyperlipidaemia is reported. Special attention is paid to early recognition of the syndrome and the prevention of complications of the several metabolic disorders that occur in this syndrome.

Abnormal responsiveness of nephrogenous cyclic AMP excretion following intravenously administered calcium in normocalcaemic squamous cell cancer patients.

The renal response to calcium infusion was compared in ten normocalcaemic patients with squamous cell cancer and in ten normocalcaemic patients with adenocarcinoma. Both groups were comparable with regard to tumour load, renal function, magnesium and 25-hydroxyvitamin D levels. After injection of 3 mg elementary Ca/kg BW nephrogenous cAMP excretion fell significantly in the group of adenocarcinoma patients (1.74 +/- 1.14 nmol/dl GF vs. 2.81 +/- 1.39 nmol/dl GF; P less than 0.01) and TmPO4/GFR rose significantly at 60 and 120 min. No fall in NcAMP excretion was observed in the group of squamous cell cancer patients (2.18 +/- 0.84 vs. 2.24 +/- 0.84 nmol/dl GF; NS) and TmPO4/GFR remained unchanged. Three of ten patients with squamous cell cancer showed a paradoxical rise in NcAMP excretion following calcium administration. The other seven patients with squamous cell cancer showed a decline in NcAMP excretion (delta NcAMP) which was significantly less than in the ten patients with adenocarcinoma (0.52 +/- 0.16 vs. 1.23 +/- 0.74 nmol/dl GF; P less than 0.05). Increased phosphaturia was observed in three of ten patients with squamous cell cancer after calcium was administered. This also occurred in the presence as well as in the absence of a paradoxical activation of the adenylate cyclase system. It is concluded that the abnormal NcAMP response to calcium-infusion in normocalcaemic squamous cell cancer patients might be due to the presence of a non-suppressible PTH-like substance in these patients.