Urinary excretion of three specific renal tubular enzymes in patients treated with nonsteroidal anti-inflammatory drugs (NSAID)

Distribution of urinary gamma-glutamyltransferase activity in 40- to 74-year-old Japanese women

Urinary gamma-glutamyltransferase (u-γGT) concentration (U/L) and excretion (urinary creatinine-corrected u-γGT; u-γGT/u-Cre, U/g creatinine) are useful markers for kidney disease. However, there is limited information available on u-γGT and u-γGT/u-Cre distribution in the elderly Japanese population. In this study, we investigated the distribution of u-γGT and u-γGT/u-Cre in 113 Japanese women aged 40–74 years. The u-γGT was assessed from spot urine samples (collected from 09:00 to 14:00) spectrophotometrically according to the Japan Society of Clinical Chemistry reference measurement procedure using l-γ-glutamyl-3-carboxy-4-nitroanilide as the substrate. The u-Cre was measured enzymatically using creatininase, creatinase, sarcosine oxidase, and peroxidase. None of the participants was diagnosed with any kidney disease. Median u-γGT and u-γGT/u-Cre values (central 95% interval values) were 29.7 (5.3–144.0) U/L and 57.9 (32.9–122.7) U/g creatinine, respectively. The distribution of u-γGT tended to decline with age. There was a statistically significant difference in the u-γGT value between the 40-59- and 60-74-year-old groups. In contrast, there was no significant difference in the u-γGT/u-Cre between each age group. The u-Cre level also declined with age. It is suggested that the decline of u-γGT with aging would be masked by the u-Cre correction.

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Median (central 95% interval values) u-γGT value was 29.7 (5.3–144.0) U/L.

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Median (central 95% interval values) u-γGT/u-Cre ratio was 57.9 (32.9–122.7) U/g creatinine.

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Distribution of u-γGT tends to decline with age.

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u-Cre levels also declined with age.

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Decline of u-γGT with aging would be masked by the u-Cre correction.

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.

Symmetric dimethyl arginine and N-acetyl-β-D-glucosaminidase lysozimuria of proximal renal tubules as a target for nephrotoxicity in patients with rheumatoid arthritis treated with disease modifying antirheumatic drugs

BACKGROUND

The aim of this study was to determine the effect of initial therapy with some disease modifying antirheumatic drugs (DMARDs) (Methotrexate and Ketoprofen) on glomerular and tubular integrity in patients with Rheumatoid arthritis (RA).

OBJECTIVES

OBJECTIVES

To determine whether there is a change in clinical and laboratory indicators of renal function in course of the follow up of treatment and whether that change correlates with the dynamics of the quantity of enzymes excreted in urine and reactants of the acute phase.

MATERIALS AND METHODS

Using colorimetric method for determination of NAG, samples of 70 participants were examined (35 RA patients treated with Ketoprofen only, 35 RA patients treated with combined use of Methotrexate and Ketoprofen). The follow up was 5 time-intervals in the course of 24 weeks.

RESULTS

There was moderate correlation between NAG and microalbuminuria (r=0,34) in the group of patients treated with Ketoprofen only, while statistically significant correlation (r=0,21) was seen in group of patients with combined use of Methotrexate and Ketoprofen. NAG enzymuria in size, number of patients registered, and time of appearance were greater and appears earlier in the group with the combined use of Methotrexate and Ketoprofen compared with the mono-therapy with Ketoprofen. Mean urinary NAG induction was increasing with the concomitant use of Methotrexate and Ketoprofen.

CONCLUSIONS

Methotrexate is more potent NAG inductor than Ketoprofen and provokes greater tubular enzymuria than Ketoprofen.

The Diagnostic Value of N-Acetyl-β-D-Glucosaminidase and Microalbumin Concentrations in Rheumatoid Arthritis

The purpose of this research was to compare the diagnostic values of laboratory variables, to present quantitative evaluations of the diagnostic sifted test with reference to sensitivity and specificity, the predictive value of the positive and negative test and precision of the test for N-acetyl-β-D-glucosa-minidase (NAG), microalbumin, rheumatoid factor (RF), Creactive protein (CRP), DAS 28 index, in early diagnosis of untreated rheumatoid arthritis (RA), and to define the effect of untreated rheumatoid arthritis on glomerular and tubular function. Using a colorimetric assay for the determination of Nacetyl-β-D-glucosaminidase and an immunoturbidimetric assay for the determination of urinary albumin, the samples of serum and urine have been examined in 70 participants (35 RA who were not treated, 35 healthy controls). RF was defined with the test for agglutination (Latex RF test) in the same participants. Out of 35 examined patients with RA, in 13 we found the presence of NAG enzymuria (sensitivity of the test 37.14%), while microalbuminuria appeared in 4 patients (sensitivity of the test 11.42%). RF appeared in 17 patients (sensitivity of the test 48.57%). Four patients were NAG and RF positive, while 3 patients were microalbuminuria and RF positive. Among 18 RF negative patients, 9 patients were NAG positive, and 1 patient presented with microalbuminuria. Among 17 RF positive RA, the presence of NAG was found in 4 patients, and the presence of microalbuminuria in 3 patients. Among 18 RF negative RA, NAG enzymuria appeared in 9 patients. Microalbuminuria was present in 1 patient. In the healthy control group, 8 patients were NAG positive, 2 patients were positive for microalbuminuria. RF appeared in 2 patients. NAG has higher sensitivity than microalbuminuria in the detection of asymptomatic renal lesions in untreated RA.

Urinary gamma-glutamyltransferase (GGT) as a potential marker of bone resorption

We recently identified gamma-glutamyltransferase (GGT) as a novel bone-resorbing factor. The present study was undertaken to determine whether GGT is a marker of bone resorption in two genetic models of hyper- and hypo-function of osteoclasts, as well as in postmenopausal women with accelerated bone resorption, using type I collagen N-telopeptide (NTX) and deoxypyridinoline (DPD) as established biochemical markers. Urinary excretion of GGT, corrected for creatinine, was found to be increased in osteoprotegerin (OPG)-deficient osteoporotic mice as well as in patients with postmenopausal osteoporosis (67-83 years of age); in both cases the urinary level decreased after treatment of patients or mice with alendronate, a selective inhibitor of bone resorption, concomitantly with a reduction in DPD and NTX. Conversely, in osteopetrotic op/op mice, urinary GGT increased in parallel with DPD after induction of osteoclasts with M-CSF injection. Constant infusion of parathyroid hormone (PTH) also increased urinary GGT along with DPD. In a survey of 551 postmenopausal women (50-89 years of age) at their regular health checkup, urinary GGT excretion exhibited a high correlation with DPD (rho = 0.49, p < 0.0001). The calculated sensitivity and specificity for diagnosing elevated bone resorption, as determined by a DPD value higher than 7.6 nM/mM Cr, were 61% and 92%, respectively, when a cut-off value of 40 IU/g Cr was assigned for urinary GGT. Since GGT activity can be measured inexpensively in large numbers in a very short time, the measurement of urinary level may provide a convenient and useful method for mass screening to identify those with increased bone turnover and hence at increased risk for bone fracture.

Using urinary biomarkers to evaluate renal effects of a Cox-2 NSAID in volunteers

We explored urinary biomarkers as an alternative for measuring the effect of an experimental COX-2 inhibitor on renal function in volunteers. Thirty male volunteers between the ages of 20-40 were enrolled and a COX-2 NSAID was given in a blinded design. The acute administration of an oral COX-2 NSAID resulted in a consistent increase in the urinary enzyme AAP at 2 hours. At 24 hours after COX-2 NSAID administration values for most of the urinary biomarkers had returned to baseline suggesting that such effects are transient and without clinical significance in situations of acute administration.