Jee-Soo Lee; Kyunghoon Lee; Sung Min Kim; Moon Suk Choi; Sun Hee Jun; Woon Heung Song; Sang Hoon Song; Kyoung Un Park; Junghan Song

doi:10.3343/lmo.2017.7.3.128

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Lee, Lee, Kim, Choi, Jun, Song, Song, Park, and Song: Effects of Pyridoxal-5′-Phosphate on Aminotransferase Activity Assay

Original Article

Lab Med Online 2017;7(3):128-134.

Published online: 17 July 2017

DOI: https://doi.org/10.3343/lmo.2017.7.3.128

Effects of Pyridoxal-5′-Phosphate on Aminotransferase Activity Assay

Jee-Soo Lee, M.D.^1,², Kyunghoon Lee, M.D.^1,^3,, Sung Min Kim, M.T.³, Moon Suk Choi, M.D.^1,², Sun Hee Jun, M.T.³, Woon Heung Song, Ph.D.⁴, Sang Hoon Song, M.D.^1,², Kyoung Un Park, M.D.^1,³, Junghan Song, M.D.^1,³

¹Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea

²Department of Laboratory Medicine, Seoul National University Hospital, Seoul, Korea

³Department of Laboratory Medicine, Seoul National University Bundang Hospital, Seongnam, Korea

⁴Department of Biomedical Laboratory Science, Shinhan University, Uijeongbu, Korea

Corresponding author: Kyunghoon Lee Department of Laboratory Medicine, Seoul National University Bundang Hospital, 82 Gumi-ro 173beon-gil, Bundang-gu, Seongnam 13620, Korea Tel: +82-31-787-7696, Fax: +82-31-787-4015, E-mail: khlee59023@gmail.com

Received 13 September 201626 October 2016 Accepted 27 October 2016

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Pyridoxal-5′-phosphate (P5P), a coenzyme of the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) reactions, is required to measure aminotransferase levels (IFCC method). However, a modified IFCC method that uses a reagent devoid of P5P is commonly used in laboratories in Korea. To determine the differences between the two methods, we compared aminotransferase levels measured by using the IFCC method and modified IFCC method.

Methods

Serum levels of AST and ALT, with and without P5P, were measured in 2,318 patients. Based on the allowable limits of performance set by the Royal College of Pathologists of Australasia (RCPA), differences between the two methods were analyzed under various conditions.

Results

Higher AST and ALT values were obtained by the IFCC method compared to modified IFCC method, showing significant differences between the two methods (AST, 5.8±14.2 IU/L; ALT, 2.8±6.9 IU/L) (P<0.001). Values exceeding RCPA criteria were more frequently observed in emergency orders (AST, 65.8%; ALT, 14.4%) than in routine orders (AST, 3.2%; ALT, 9.6%), as well as in inpatient wards (AST, 70.4%; ALT, 18.5%) compared to outpatient clinics (AST, 56.6%; ALT, 10.0%). However, the differences between the two methods were not significant among the disease groups, except for the acute myocardial infarction group.

Conclusions

The method using reagents without P5P underestimated aminotransferase activity. The effect of P5P was more significant in patients with acute myocardial infarction, considered as P5P-deficient. In conclusion, the IFCC method with P5P should be applied for measuring AST and ALT serum levels.

Keywords: Liver function tests, Alanine aminotransferases, Aspartate aminotransferases, Pyridoxal phosphate

REFERENCES

1. McPherson RA, Pincus MR. Henry's clinical diagnosis and management by laboratory methods. Elsevier Health Sciences. 2016. 295–6.

2. Schumann G, Bonora R, Ceriotti F, Ferard G, Ferrero CA, Franck PF, et al. IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 4. Reference procedure for the measurement of catalytic concentration of alanine aminotransferase. Clin Chem Lab Med. 2002; 40:718–24.

3. Schumann G, Bonora R, Ceriotti F, Ferard G, Ferrero CA, Franck PF, et al. IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. International Federation of Clinical Chemistry and Laboratory Medicine. Part 5. Reference procedure for the measurement of catalytic concentration of aspartate aminotransferase. Clin Chem Lab Med. 2002; 40:725–33.

4. Horder M, Moore RE, Bowers GN Jr. Aspartate aminotransferase activity in human serum. Factors to be considered in supplementation with pyridoxal 5'-phosphate in vitro. Clin Chem. 1976; 22:1876–83.

5. Jun SH, Song J. Annual report on the external quality assessment scheme for clinical chemistry in Korea (2014). J Lab Med Qual Assur. 2015; 37:115–23.

6. Chasan-Taber L, Selhub J, Rosenberg IH, Malinow MR, Terry P, Tishler PV, et al. A prospective study of folate and vitamin B6 and risk of myocardial infarction in US physicians. J Am Coll Nutr. 1996; 15:136–43.

7. Roubenoff R, Roubenoff RA, Selhub J, Nadeau MR, Cannon JG, Freeman LM, et al. Abnormal vitamin B6 status in rheumatoid cachexia. Association with spontaneous tumor necrosis factor alpha production and markers of infammation. Arthritis Rheum. 1995; 38:105–9.

8. Kok FJ, Schrijver J, Hofman A, Witteman JC, Kruyssen DA, Remme WJ, et al. Low vitamin B6 status in patients with acute myocardial infarction. Am J Cardiol. 1989; 63:513–6.

9. Jones GR, Sikaris K, Gill J. ‘Allowable limits of performance’ for external quality assurance programs - an approach to application of the Stockholm Criteria by the RCPA Quality Assurance Programs. Clin Biochem Rev. 2012; 33:133–9.

10. Tutor-Crespo MJ, Hermida J, Tutor JC. Activation of serum aminotransferases by pyridoxal-5´-phosphate in epileptic patients treated with anticonvulsant drugs. Clin Biochem. 2004; 37:714–7.

11. Gressner AM, Sittel D. Plasma pyridoxal 5´-phosphate concentrations in relation to apo-aminotransferase levels in normal, uraemic, and post-myocardial infarct sera. J Clin Chem Clin Biochem. 1985; 23:631–6.

12. Ross AC. Modern nutrition in health and disease. Wolters Kluwer Health/Lippincott Williams & Wilkins. 2014. 452–9.

13. Institute of Medicine Standing Committee on the Scientifc Evaluation of Dietary Reference I, its Panel on Folate OBV, Choline. The National Academies Collection: Reports funded by National Institutes of Health. Dietary Reference Intakes for Thiamin, Ribofavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington (DC): National Academies Press (US) National Academy of Sciences;1998.

14. Molina-Lopez J, Florea D, Quintero-Osso B, de la Cruz AP, Rodriguez-Elvira M, Del Pozo EP. Pyridoxal-5'-phosphate defciency is associated with hyperhomocysteinemia regardless of antioxidant, thiamine, ribofavin, cobalamine, and folate status in critically ill patients. Clin Nutr. 2016; 35:706–12.

15. Jamieson CP, Obeid OA, Powell-Tuck J. The thiamin, ribofavin and pyridoxine status of patients on emergency admission to hospital. Clin Nutr. 1999; 18:87–91.

16. Labadarios D, Brink PA, Weich HF, Visser L, Louw ME, Shephard GS, et al. Plasma vitamin A, E, C and B6 levels in myocardial infarction. S Af Med J. 1987; 71:561–3.

17. Giannini EG, Testa R, Savarino V. Liver enzyme alteration: a guide for clinicians. CMAJ. 2005; 172:367–79.

18. CLIA Requirements for Analytical Quality. https://www.westgard.com/clia.htm.

19. Ricos C, Alvarez V, Cava F, Garcia-Lario JV, Hernandez A, Jimenez CV, et al. Desirable Specifcations for Total Error, Imprecision, and Bias, derived from intra- and inter-individual biologic variation. https://www.westgard.com/biodatabase1.htm. (Updated on 2014).

Fig. 1.

Bland-Altman plots for AST (IU/L) (A and B) and ALT (IU/L) (C and D) performed as emergency tests. Red lines represent allowable limits of performance.

Fig. 2.

Bland-Altman plots for AST (IU/L) (A and B) and ALT (IU/L) (C and D) performed as routine tests. Red lines represent allowable limits of performance.

Table 1.

Aminotransferase levels measured by the two methods

	IFCC	Modified IFCC	Difference^∗ (IU/L)	P-value
AST (IU/L)	41.6±62.1	35.7±51.3	5.8±14.2	<0.001
ALT (IU/L)	22.4_±35.8	19.6_±30.6	2.8_±6.9	_<0.001

Values are presented as the mean±standard deviation. Paired t-test was used to compare mean values.

^∗ Difference=[IFCC-Modified IFCC] (IU/L).

Abbreviations: AST, aspartate aminotransferase; ALT, alanine aminotransferase.

Table 2.

Distributions of aminotransferase results in subgroups according to the types of order and status

Group	AST			ALT
Group	Difference^∗ (IU/L)	Exceed the limits %	P value	Difference^∗ (IU/L)	Exceed the limits N (%)	P value
Type of order			<0.001			<0.001
Emergency order	11.1±19.9	65.8 (648/985)		3.0±8.1	14.4 (142/985)
Routine order	1.9±5.0	3.2 (43/1333)		2.6±5.8	9.6 (128/1333)
Status			0.001			0.004
Inpatient ward	13.4±20.9	70.4 (190/270)		4.1±12.5	18.5 (50/270)
Emergency room	13.6_±38.1	65.2 (86/132)		2.0_±3.7	9.8 (13/132)
Outpatient clinic	7.6±7.8	56.6 (141/249)		.0±3.2	10.0 (25/249)

Chi-square test was used to compare percentages of exceeding the allowable limits of performance set by the RCPA.

^∗ Difference=[IFCC-Modified IFCC] (IU/L). Values are presented as the mean±standard deviation.

Abbreviations: AST, aspartate aminotransferase; ALT, alanine aminotransferase.

Table 3.

Distribution ns of aminotransferase r esults in subgroups accordi ing to various diseases

Disease	AST			ALT
Disease	Difference^∗ (IU/L)	Exceed the limits, %	P value	Difference^∗ (IU/L)	Exceed the limits, %	P value
CKD			0.121			0.059
Yes	6.8_±4.1	47.8 (11/23)		0.5_±2.0	0.0 (0/23)
No	11.4±22.9	64.6 (406/628)		2.9±8.6	14.0 (88/628)
Liver disease			0.295			0.054
Yes	20.8_±39.4	71.2 (37/52)		9.1_±25.1	23.1 (12/52)
No	10.4±20.2	63.4 (380/599)		2.3±4.6	12.7 (76/599)
Malignancy			0.141			0.253
Yes	10.1±18.6	61.2 (200/327)		3.0±10.7	11.9 (39/327)
No	12.4_±25.8	67.0 (217/324)		2.7_±5.4	15.1 (49/324)
Infection			0.115			0.461
Yes	10.9±13.1	54.9 (39/71)		3.0±5.9	9.9 (7/71)
No	11.3_±23.4	65.2 (378/580)		2.8_±8.8	14.0 (81/580)
AMI			<0.001			0.002
Yes	41.0±82.0	100.0 (23/23)		6.0±5.9	39.1 (9/23)
No	10.1±16.0	62.7 (394/628)		2.7±8.6	12.6 (79/628)
Other diseases			0.161			0.140
Yes	10.4±13.0	68.0 (140/206)		2.7±5.6	16.5 (34/206)
No	11.6±25.7	62.2 (277/445)		2.9±9.5	12.1 (54/445)

Fisher's exact test was used to compare percentages exceeding the allowable limits of performance set by the RCPA. Other diseases included 41 various diseases.

^∗ Difference=[IFCC-Modified IFCC] (IU/L). Values are presented as the mean±standard deviation. Abbreviations: CKD, chronic kidney disease; AMI, acute myocardial infarction; AST, aspartate aminotransferase; ALT, alanine aminotransferase.

Table 4.

Frequencies of exceeded limits according to three criteria

	Exceed the limits, %
	AST ≤40 IU/L	AST >40 IU/L	ALT ≤40 IU/L	ALT >40 IU/L
RCPA [9]	24.4 (469/1926)	56.6 (222/392)	7.2 (153/2138)	65.0 (117/180)
CLIA [18]	32.0 (616/1926)	35.2 (138/392)	28.8 (616/2138)	21.7 (39/180)
Westgard [19]	40.2 (775/1926)	44.1 (173/392)	18.9 (405/2138)	10.6 (19/180)

Abbreviations: AST, aspartate aminotransferase; ALT, alanine aminotransferase.

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