Variability and lability of ammonia levels in healthy volunteers and patients with cirrhosis: Implications for trial design and clinical practice

Jasmohan S. Bajaj; Patricia Pringle Bloom; Raymond T. Chung; Tarek I. Hassanein; Marielys Padilla-Martinez; Zeid Kayali; Don C. Rockey; Roula Sasso; Alagar R. Muthukumar; William M. Lee; William S. Denney; Edith A. Gavis; Cami Anderson; Larry Blankstein; Aoife M. Brennan; Marja K. Puurunen; Eric Lawitz

doi:10.14309/ajg.0000000000000384

Variability and lability of ammonia levels in healthy volunteers and patients with cirrhosis: Implications for trial design and clinical practice

Jasmohan S. Bajaj, Patricia Pringle Bloom, Raymond T. Chung, Tarek I. Hassanein, Marielys Padilla-Martinez, Zeid Kayali, Don C. Rockey, Roula Sasso, Alagar R. Muthukumar, William M. Lee, William S. Denney, Edith A. Gavis, Cami Anderson, Larry Blankstein, Aoife M. Brennan, Marja K. Puurunen, Eric Lawitz

Division of Gastroenterology

Research output: Contribution to journal › Article › peer-review

28 Scopus citations

Abstract

INTRODUCTION: Ammonia levels are used to assess hepatic encephalopathy, but their levels are highly variable in clinical practice. METHODS: We studied factors associated with variation in ammonia values in cirrhotic patients without previous hepatic encephalopathy and healthy volunteers (HVs). RESULTS: Ammonia increased by 12% and 18% at 1 and 2 hour, respectively, after a protein meal in 64 cirrhotic patients (P < 0.001). In 237 HVs, ammonia levels varied significantly between sites (P < 0.0001). New site-specific ammonia upper limits based on HV levels using a strict analysis protocol differed from routinely used values. Correlation between paired fresh samples was high (r 5 0.83) but modest between fresh and frozen samples (r 5 0.62). DISCUSSION: Sample handling, processing, and protein intake impact ammonia levels across sites.

Original language	English (US)
Pages (from-to)	783-785
Number of pages	3
Journal	American Journal of Gastroenterology
Volume	115
Issue number	5
DOIs	https://doi.org/10.14309/ajg.0000000000000384
State	Published - 2020

ASJC Scopus subject areas

Gastroenterology
Hepatology

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10.14309/ajg.0000000000000384

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Bajaj, J. S., Bloom, P. P., Chung, R. T., Hassanein, T. I., Padilla-Martinez, M., Kayali, Z., Rockey, D. C., Sasso, R., Muthukumar, A. R., Lee, W. M., Denney, W. S., Gavis, E. A., Anderson, C., Blankstein, L., Brennan, A. M., Puurunen, M. K., & Lawitz, E. (2020). Variability and lability of ammonia levels in healthy volunteers and patients with cirrhosis: Implications for trial design and clinical practice. American Journal of Gastroenterology, 115(5), 783-785. https://doi.org/10.14309/ajg.0000000000000384

Bajaj, JS, Bloom, PP, Chung, RT, Hassanein, TI, Padilla-Martinez, M, Kayali, Z, Rockey, DC, Sasso, R, Muthukumar, AR, Lee, WM, Denney, WS, Gavis, EA, Anderson, C, Blankstein, L, Brennan, AM, Puurunen, MK & Lawitz, E 2020, 'Variability and lability of ammonia levels in healthy volunteers and patients with cirrhosis: Implications for trial design and clinical practice', American Journal of Gastroenterology, vol. 115, no. 5, pp. 783-785. https://doi.org/10.14309/ajg.0000000000000384

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title = "Variability and lability of ammonia levels in healthy volunteers and patients with cirrhosis: Implications for trial design and clinical practice",

abstract = "INTRODUCTION: Ammonia levels are used to assess hepatic encephalopathy, but their levels are highly variable in clinical practice. METHODS: We studied factors associated with variation in ammonia values in cirrhotic patients without previous hepatic encephalopathy and healthy volunteers (HVs). RESULTS: Ammonia increased by 12% and 18% at 1 and 2 hour, respectively, after a protein meal in 64 cirrhotic patients (P < 0.001). In 237 HVs, ammonia levels varied significantly between sites (P < 0.0001). New site-specific ammonia upper limits based on HV levels using a strict analysis protocol differed from routinely used values. Correlation between paired fresh samples was high (r 5 0.83) but modest between fresh and frozen samples (r 5 0.62). DISCUSSION: Sample handling, processing, and protein intake impact ammonia levels across sites.",

author = "Bajaj, {Jasmohan S.} and Bloom, {Patricia Pringle} and Chung, {Raymond T.} and Hassanein, {Tarek I.} and Marielys Padilla-Martinez and Zeid Kayali and Rockey, {Don C.} and Roula Sasso and Muthukumar, {Alagar R.} and Lee, {William M.} and Denney, {William S.} and Gavis, {Edith A.} and Cami Anderson and Larry Blankstein and Brennan, {Aoife M.} and Puurunen, {Marja K.} and Eric Lawitz",

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year = "2020",

doi = "10.14309/ajg.0000000000000384",

language = "English (US)",

volume = "115",

pages = "783--785",

journal = "American Journal of Gastroenterology",

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T1 - Variability and lability of ammonia levels in healthy volunteers and patients with cirrhosis

T2 - Implications for trial design and clinical practice

AU - Bajaj, Jasmohan S.

AU - Bloom, Patricia Pringle

AU - Chung, Raymond T.

AU - Hassanein, Tarek I.

AU - Padilla-Martinez, Marielys

AU - Kayali, Zeid

AU - Rockey, Don C.

AU - Sasso, Roula

AU - Muthukumar, Alagar R.

AU - Lee, William M.

AU - Denney, William S.

AU - Gavis, Edith A.

AU - Anderson, Cami

AU - Blankstein, Larry

AU - Brennan, Aoife M.

AU - Puurunen, Marja K.

AU - Lawitz, Eric

PY - 2020

Y1 - 2020

N2 - INTRODUCTION: Ammonia levels are used to assess hepatic encephalopathy, but their levels are highly variable in clinical practice. METHODS: We studied factors associated with variation in ammonia values in cirrhotic patients without previous hepatic encephalopathy and healthy volunteers (HVs). RESULTS: Ammonia increased by 12% and 18% at 1 and 2 hour, respectively, after a protein meal in 64 cirrhotic patients (P < 0.001). In 237 HVs, ammonia levels varied significantly between sites (P < 0.0001). New site-specific ammonia upper limits based on HV levels using a strict analysis protocol differed from routinely used values. Correlation between paired fresh samples was high (r 5 0.83) but modest between fresh and frozen samples (r 5 0.62). DISCUSSION: Sample handling, processing, and protein intake impact ammonia levels across sites.

AB - INTRODUCTION: Ammonia levels are used to assess hepatic encephalopathy, but their levels are highly variable in clinical practice. METHODS: We studied factors associated with variation in ammonia values in cirrhotic patients without previous hepatic encephalopathy and healthy volunteers (HVs). RESULTS: Ammonia increased by 12% and 18% at 1 and 2 hour, respectively, after a protein meal in 64 cirrhotic patients (P < 0.001). In 237 HVs, ammonia levels varied significantly between sites (P < 0.0001). New site-specific ammonia upper limits based on HV levels using a strict analysis protocol differed from routinely used values. Correlation between paired fresh samples was high (r 5 0.83) but modest between fresh and frozen samples (r 5 0.62). DISCUSSION: Sample handling, processing, and protein intake impact ammonia levels across sites.

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Variability and lability of ammonia levels in healthy volunteers and patients with cirrhosis: Implications for trial design and clinical practice

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