Clinical Chemistry Lab PDF 2024-2025

MLS 3101: CLINICAL CHEMISTRY I LABORATORY CREATININE Mrs. Arlene Laquian, RMT, MBio │ Mrs. Joy G. Raso, PhD │ Mrs. Ma. Novie Carillo, MD 1st Semester A.Y. 2024-2025...

MLS 3101: CLINICAL CHEMISTRY I LABORATORY CREATININE Mrs. Arlene Laquian, RMT, MBio │ Mrs. Joy G. Raso, PhD │ Mrs. Ma. Novie Carillo, MD 1st Semester A.Y. 2024-2025 dehydrogenase, to result in a change in absorbance OUTLINE at 340 nm. I. Introduction IV. Enzymatic Method b. Creatinase-Hydrogen peroxide Method a. Functions of V. Kinetic - Jaffe Method kidney VI. Clinical Significance II. Creatinine a. Creatinine Reference Value III. Chemical Methods V. KINETIC - JAFFE METHOD PRINCIPLE: The assay is based on the reaction of creatinine with sodium picrate as described by Jaffe. Creatinine reacts with alkaline picrate forming a orange-red colored complex. I. INTRODUCTION The intensity of the color formed is proportional to the Kidneys are paired, bean- shaped organs creatinine concentration in the sample. Lie asymmetrically, the right kidney is lower than the left as the Storage and Stability: right side of the abdominal cavity is occupied by the liver ○ All the components of the kit are stable until the Each kidney is 10cm long, 6 cm wide, and 4 cm thick and expiration date on the label when stored tightly weighs 200-250g in adults. closed at 2-8°C, protected from light and Principal excretory organs in man through which the contaminations prevented during their use. nitrogenous metabolic wastes are eliminated in the form of ○ Do not use reagents over the expiration date. urine ○ Signs of reagent deterioration: A. FUNCTIONS OF KIDNEY a. presence of particles and turbidity. The functional unit of the kidney is the nephron, which b. Blank absorbance (A) at 492 nm > 1.80 consists of the glomerulus, proximal and distal tubules, Samples : Serum or heparinized plasma Creatinine stability: loop of Henle and collecting duct. 24 hours at 2-8°C. Urine dilute sample with 1:50 distilled water ○ Elimination of waste products and multiply result with dilution factor(50). ○ Maintenance of blood volume Procedure: ○ Maintenance of electrolyte balance 1. Assay conditions: ○ Maintenance of acid- base balance (pH) - Wavelength: … 492 nm (490-510) ○ Endocrine function (erythropoetin secretion) - Cuvette:... 1 cm. light path - Temperature... 37°C / 15-25°C II. CREATININE 2. Adjust the instrument to zero with distilled water. End product of muscle contraction and metabolism. 3. Pipette into a cuvette: About 5% of the total NPN; filtered and secreted but not reabsorbed by renal tubules. Synthesized from creatine (2- methyl guanido acetic acid). Creatinine is formed from 3 amino acids: methionine, arginine, glycine. 4. Mix and start stopwatch Excreted by the kidney. 5. Read the absorbance Level is affected by muscle mass of an individual. Steps in the synthesis of creatinine are: Calculations: ○ Formation of guanido-acetic acid. ○ Methylation to form creatine (in the liver) ○ Conversion of creatine to creatine phosphate by the senzyme creatine kinase (in the muscle). ○ Non-enzymatic dehydration of creatine phosphate to form creatinine (occurs in the muscle) VI. CREATININE CLINICAL SIGNIFICANCE Elevated level is associated with: It does not increase until renal function is substantially ○ a blocked urinary tract impaired. Considered as a more reliable test for renal ○ kidney problems, such as kidney damage or pathology and screening test for index of overall renal function infection Urinary output is within 1-2 g/24 hours ○ reduced blood flow to the kidneys due to shock Creatine, on the other hand is not usually measured ○ congestive heart failure, or complications of Test Considerations: diabetes ○ Plasma or serum is preferred over whole blood ○ chronic kidney injury ○ When doing the test, the fresh alkaline picrate Falsely elevated due to: solution must be used within 30 minutes. ○ Dehydration ○ Fasting is not required, but high-protein diet should ○ a very high-protein diet be avoided. ○ If Urine is use it should be refrigerated after collection or frozen if to be stored for > 4 days References: Bishop, M. L. et al., (2013). Clinical Chemistry Principles , Techniques A. CREATININE REFERENCE VALUE Correlations, 7th ed., Lippincott Williams and Wilkins, Philadelphia. Plasma or serum : Rodriguez, Maria Teresa T. (2012). Clinical Chemistry Review Handbook ○ Adult: 0.6 - 1.2 mg/dL (53 - 106 umol/L) for Medical Technologist , Medical Technology Review and Study Guide ○ Children