Michael Emmett M.D.

Wiederkehr, M. R., A. N. Mehta and M. Emmett (2019). “Case report: Patiromer-induced hypercalcemia.” Clin Nephrol Case Stud 7: 51-53.

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Patiromer is a novel potassium-binding compound which has recently received FDA approval. This ion exchange resin releases calcium when it binds potassium. We describe the development of hypercalcemia after initiation of patiromer. The calcium levels fell when the drug was stopped but recurred when it was later resumed. Patiromer was again discontinued, and the serum calcium level fell back into the normal range. We believe this patient manifested patiromer-induced hypercalcemia.

Asrani, S. K., L. W. Jennings, J. F. Trotter, J. Levitsky, M. K. Nadim, W. R. Kim, S. A. Gonzalez, B. Fischbach, R. Bahirwani, M. Emmett and G. Klintmalm (2019). “A Model for Glomerular Filtration Rate Assessment in Liver Disease (GRAIL) in the Presence of Renal Dysfunction.” Hepatology 69(3): 1219-1230.

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Estimation of glomerular filtration rate (eGFR) in patients with liver disease is suboptimal in the presence of renal dysfunction. We developed a model for GFR assessment in liver disease (GRAIL) before and after liver transplantation (LT). GRAIL was derived using objective variables (creatinine, blood urea nitrogen, age, gender, race, and albumin) to estimate GFR based on timing of measurement relative to LT and degree of renal dysfunction (www.bswh.md/grail). The measured GFR (mGFR) by iothalamate clearance (n = 12,122, 1985-2015) at protocol time points before/after LT was used as reference. GRAIL was compared with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD-4, MDRD-6) equations for mGFR < 30 mL/min/1.73 m(2) . Prediction of development of chronic kidney disease (mGFR < 20 mL/min/1.73 m(2) , initiation of chronic dialysis) and listing or receipt of kidney transplantation within 5 years was examined in internal cohort (n = 785) and external validation (n = 68,217, 2001-2015). GRAIL had less bias and was more accurate and precise as compared with CKD-EPI, MDRD-4, and MDRD-6 at time points before/after LT for low GFR. For mGFR < 30 mL/min/1.73 m(2) , the median difference (eGFR-mGFR) was GRAIL: 5.24 (9.65) mL/min/1.73 m(2) as compared with CKD-EPI: 8.70 (18.24) mL/min/1.73 m(2) , MDRD-4: 8.82 (17.38) mL/min/1.73 m(2) , and MDRD-6: 6.53 (14.42) mL/min/1.73 m(2) . Before LT, GRAIL correctly classified 75% as having mGFR < 30 mL/min/1.73 m(2) versus 36.1% (CKD-EPI), 36.1% (MDRD-4), and 52.8% (MDRD-6) (P < 0.01). An eGFR < 30 mL/min/1.73 m(2) by GRAIL predicted development of CKD (26.9% versus 4.6% CKD-EPI, 5.9% MDRD-4, and 10.5% MDRD-6) in center data and needing kidney after LT (48.3% versus 22.0% CKD-EPI versus 23.1% MDRD-4 versus 48.3% MDRD-6, P < 0.01) in national data within 5 years after LT. Conclusion: GRAIL may serve as an alternative model to estimate GFR among patients with liver disease before and after LT at low GFR.

Asrani, S. K., L. W. Jennings, J. F. Trotter, J. Levitsky, M. K. Nadim, W. R. Kim, S. A. Gonzalez, B. Fischbach, R. Bahirwani, M. Emmett and G. Klintmalm (2018). “A model for Glomerular filtration Rate Assessment In Liver disease (GRAIL) in the presence of renal dysfunction.” Hepatology Oct 19. [Epub ahead of print].

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Estimation of glomerular filtration rate (eGFR) in patients with liver disease is suboptimal in presence of renal dysfunction. We developed a model for GFR Assessment In Liver disease (GRAIL) before and after liver transplantation (LT). GRAIL was derived using objective variables (creatinine, blood urea nitrogen, age, gender, race, albumin) to estimate GFR based on timing of measurement relative to LT and degree of renal dysfunction. Measured GFR (mGFR) by iothalamate clearance (n=12,122, 1985-2015) at protocol time points before/after LT was used as reference. GRAIL was compared to Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD-4, MDRD-6) equations for mGFR<30ml/min/1.73m(2) . Prediction of development of chronic kidney disease (mGFR < 20ml/min/1.73m(2) , initiation of chronic dialysis) and listing or receipt of kidney transplantation within 5 years was examined in internal cohort (n=785) and external validation (n=68,217, 2001-2015). GRAIL had less bias, was more accurate and precise as compared to CKD-EPI, MDRD-4 and MDRD-6 at time points before/after LT for low GFR. For mGFR<30ml/min/1.73m(2) , the median difference (eGFR-mGFR) was GRAIL: 5.24 [9.65] ml/min/1.73m(2) as compared to CKD-EPI: 8.70 [18.24]ml/min/1.73m(2) , MDRD-4: 8.82 [17.38]ml/min/1.73m(2) , and MDRD-6: 6.53[14.42] ml/min/1.73m(2) . Prior to LT, GRAIL correctly classified 75% as having mGFR<30ml/min/1.73m(2) vs. 36.1% (CKD-EPI), 36.1%(MDRD-4), and 52.8%(MDRD-6).(p<0.01) An eGFR<30ml/min/1.73m(2) by GRAIL predicted development of CKD (26.9% vs. 4.6% CKD-EPI, 5.9% MDRD-4, and 10.5% MDRD-6) in center data and needing kidney after LT (48.3% vs. 22.0% CKD-EPI vs. 23.1% MDRD-4 vs. 48.3% MDRD-6, p<0.01) in national data within 5 years after LT. CONCLUSION: GRAIL may serve as an alternative model to estimate GFR amongst patients with liver disease before and after LT at low GFR.

Gupta, S., J. J. Gao, M. Emmett and A. Z. Fenves (2017). “Topiramate and metabolic acidosis: An evolving story.” Hosp Pract (1995) 45(5): 192-195.

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Topiramate is an anticonvulsant that is being increasingly used for a number of different off-label indications. Its inhibition of carbonic anhydrase isoenzymes can lead to metabolic acidosis, elevated urine pH, reduced urine citrate, and hypercalciuria, thereby creating a milieu that is ripe for calcium phosphate stone formation. In this review, we describe a case of topiramate-induced metabolic acidosis. We review the frequency of metabolic acidosis among children and adults, as well as the mechanism of hyperchloremic metabolic acidosis and renal tubular acidosis in topiramate users. Finally, we describe the long-term effects of topiramate-induced metabolic acidosis, including nephrolithiasis, nephrocalcinosis, and bone degradation. Patients who are prescribed topiramate should be carefully monitored for metabolic derangements, and they may benefit from alkali supplementation, or in extreme cases, discontinuation of the drug altogether.

Gupta, S., J. J. Gao, M. Emmett and A. Z. Fenves (2017). “Topiramate and metabolic acidosis: An evolving story.” Hosp Pract (1995): 1-4.

Full text of this article.

Topiramate is an anticonvulsant that is being increasingly used for a number of different off-label indications. Its inhibition of carbonic anhydrase isoenzymes can lead to metabolic acidosis, elevated urine pH, reduced urine citrate, and hypercalciuria, thereby creating a milieu that is ripe for calcium phosphate stone formation. In this review, we describe a case of topiramate-induced metabolic acidosis. We review the frequency of metabolic acidosis among children and adults, as well as the mechanism of hyperchloremic metabolic acidosis and renal tubular acidosis in topiramate users. Finally, we describe the long-term effects of topiramate-induced metabolic acidosis, including nephrolithiasis, nephrocalcinosis, and bone degradation. Patients who are prescribed topiramate should be carefully monitored for metabolic derangements, and they may benefit from alkali supplementation, or in extreme cases, discontinuation of the drug altogether.