Easy Biochemistry Notes

  Dyslipidemia - Laboratory Analysis is by Lipid Profile estimation Lipid profile  - consists of  Total Cholesterol Triglycerides HDL LDL VLDL HDL/LDL ratio Total Cholesterol/HDL ratio

 Thyroid disorders are analysed using the Thyroid function tests/Thyroid Profile 1. T3/T4 assay -  Total T3/T4 & Free T3 & T4 - analysed by radioimmunoassay(RIA) or ELISA or CLIA(chemiluminescence assay) or Fluorescent immunoassay(FIA) Normal Level  T3 - 1.8 - 3 nmol/L T4 - 65-150 nmol/L f T3 - 0.3% of total T3 f T4 - 0.03% of total T4 2.Plasma TSH Normal level - 0.5-5 mU/L TSH is produced by pituitary gland  its secretion is regulated by the feedback mechanism of fT3 & fT4 secretion 3.Thyroid Antibodies Thyroid stimulating immunoglobulin(TSIg) is the antibody generated against the TSH receptor Measurement of TSIg  help in the diagnosis of Graves disease. Antibodies to thyroid peroxidase - Measurement of Anti-TPO antibodies help in the diagnosis of Hashimoto's thyroiditis(autoimmune thyroiditis) 4.Radioactive Iodine uptake To study the thyroid structure & function Radioactive iodine is given and the radio scan of thyroid gland is done to check ...

Arterial Blood Gas Analysis (ABG) Helps in detecting acid base disorders like  Metabolic Acidosis & Alkalosis  Respiratory Acidosis & Alkalosis 1.Blood pH -  Normal pH - 7.35 - 7.45 helps in checking acidosis/alkalosis < 7.35 - acidosis >7.45 - alkalosis 2.HCO3- Normal value - 22-28 mmol/l 3.PCO2 Normal Value - 35-48 mmHg helps in checking CO2 retention Increase/Decrease seen in respiratory disorders 4.PO2 normal Value - 95-98% helps in checking blood oxygen saturation 5.Electrolytes  Electrolyte estimation tells about the anion gap Normal Level  Na+ - 135-145 meq/l K+ - 3.5-4.5 meq/l Cl- - 96-105  meq/l Ca++ - 9-11 mg/dl 6.Other investigations to know the cause RFT Blood Glucose Serum Lactate Urine & Plasma Ketones

Clinical Manifestations of Liver Dysfunction Jaundice Portal Hypertension Bleeding oesophageal varices Ascites Spontaneous bacterial peritonitis Hepatic encephalopathy Hepatorenal syndrome Disordered haemostasis in liver diseases- e.g.-dysfibrinogenemia, thrombocytopenia I.Serum Bilirubin   Serial measurement of bilirubin helps assess the severity of liver damage in several types of liver disease (e.g., alcoholic hepatitis, cirrhosis). In acute hepatitis, bilirubin peaks later than enzymes do, and serum bilirubin remains elevated for longer than urine bilirubin because of the presence of biliprotein (δ-bilirubin). In most liver diseases there is an increase in conjugated bilirubin whereas increases in unconjugated bilirubin mostly are due to causes other than liver diseases II.Serum Albumin Serum albumin measurements are useful in assessing the chronicity of the disease. The serum albumin concentration is decreased in 1.      Severe acute liver disease 2. ...

DEFINITION - Jaundice is the yellowish discoloration of the skin and mucous membrane due to hyperbilirubinemia and deposition of bile pigments. •It is clinically detectable when the plasma bilirubin exceeds >3 mg/dl. • Jaundice is the clinical term. • Icterus is the Greek term for jaundice •Normal plasma bilirubin level ranges from 0.2–0.8 mg/ dL. •The Unconjugated Bilirubin is about 0.2–0.6 mg/dL, while Conjugated Bilirubin is about 0–0.2 mg/dL. •If the plasma bilirubin level exceeds 1 mg/dL , the condition is called hyperbilirubinemia. •Levels between 1 and 2 mg/dL are indicative of latent jaundice.   CAUSES OF JAUNDICE SAMPLES USED FOR DIAGNOSIS OF JAUNDICE 1.      Blood 2.      Urine 3.      Stool 1.LAB DIAGNOSIS USING BLOOD SAMPLE Tests to assess serum bilirubin-  Vandenberg  Reaction Bilirubin reacts with diazo reagent (diazotized sulfanilic acid) to produce colored azo pigm...

Enzyme diagnosis is required for MI as : a) 25 to 30% of MI cases or not diagnosed antemortem. b) Clinical diagnosis and angiographic studies do not correlate in 25 to 30% of patients c) ECG findings may not be helpful if Prior left bundle branch block is present Presence of Old changes that may mask current ECG interpretation Intravascular infarction may not change ECG pattern Diaphragmatic infarction often missed on ECG

Inflammation of the pancreas is called pancreatitis. It can be Acute , i.e., a sudden inflammation of the pancreas. The causes for this condition can be many but most commonly due to gall stone obstruction and long term alcohol abuse Chronic , i.e., prolonged inflammation. The most common cause is long term alcohol abuse Lab diagnosis of pancreatitis is mainly made by measuring the enzyme levels like   serum lipase and serum amylase  I)Serum lipase levels – It is the preferred test It is the major lipolytic enzyme that hydrolyses glycerol esters of long-chain fatty acids. It is more specific than amylase as it is not elevated in salivary diseases. Acute pancreatitis - increases within 3–6 hours with a peak at 24 hours, usually returns to normal within 8–14 days. It remains elevated even after amylase returns to normal. Urinary lipase is not clinically useful Lipase: amylase ratio >3 (and especially >5) indicates alcoholic rather than non-alcoholic pancreatitis. In ch...

HbA 1 C or glycated hemoglobin is a derivative formed when adult hemoglobin(protein) reacts spontaneously with glucose(a reducing sugar) There are different types of glycated hemoglobin molecules, all are together called HbA 1  fraction In HbA 1 fraction - 80% molecules are HbA 1 C - glucose is attached to N-terminal valine of beta polypeptide of the hemoglobin molecule HbA 1 A 1 - fructose 1.6 bisphosphate is attached to valine HbA 1 A 2 - glucose 6 phosphates are attached to n terminal valine HbA 1 D - glucose is attached to the lysine residue of alpha or beta chain. Non-enzymatic addition of aldehyde of glucose to the N-terminal valine of beta polypeptide of hemoglobin molecule to form keto amine . In general, the concentration of hba1c in the blood is very low, contributing to 5% of total hemoglobin but when the blood glucose concentration is more as see in diabetes the hba1c concentration is more. The increased concentration of glucose increases the formation of HbA 1 C...

GOUT - LABORATORY ANALYSIS Serum Uric Acid  > 7 mg/dl - hyperuricemia - uric acid more than 7mg/dl forms monosodium urate crystals and gets deposited Urinary  Analysis for Uric Acid crystals & urinary pH Synovial Biopsy   for Synovial Fluid Analysis - shows uric acid crystals & " Tophi " - Needle shaped crystals Chronic cases of Gout - Blood Urea Nitrogen , Serum Creatinine , GFR,Proteinuria,Serum Electrolytes Plain Radiographs - showing joint destruction Ultrasound for evaluation of Renal Stones OEDEMA - CAUSES Congestive Heart Failure Nephrotic Syndrome - Kidney dysfunctioning,Hypoalbuminemia,Proteinuria Cirrhosis of Liver - Hepatic Dysfunctioning CONGESTIVE HEART FAILURE - LABORATORY ANALYSIS NT-PRO BNP - (N-terminal pro brain natriuretic peptide) - >25pg/ml indicates heart failure NEPHROTIC SYNDROME - LABORATORY ANALYSIS KIDNEY FUNCTIONING -  LABORATORY ANALYSIS Blood Urea Serum Creatinine GFR Serum Electrolytes Urinary Protein Excretion ...

  MYOCARDIAL INFARCTION - LABORATORY ANALYSIS Cardiac Markers Enzymes - CK-MB, SGOT, LDH Proteins - Troponin-T,Troponin-I,Myoglobin Inflammatory Markers - CRP, Amyloid- A,WBC  Cardiac Risk Evaluation Test Total Cholesterol LDL cholesterol HDL Cholesterol Triglycerides VLDL cholesterol RENAL FAILURE - LABORATORY ANALYSIS Blood Urea Serum Creatinine Blood Urea Nitrogen(BUN) Serum & Urinary Phosphorus Serum & Urinary Calcium Serum & Urinary Protein Serum Albumin Creatinine Clearance Urea Clearance Inulin Clearance Dilution & concentration Tests Serum & Urinary Electrolytes

Diabetes Mellitus – Laboratory analysis FBS with corresponding urine sugar PLBS with corresponding urine sugar RBS HbA1C Oral Glucose Tolerance Test(OGTT) Glucose Challenge Test(GCT) in Gestational Diabetes Mellitus Novel markers -  Fructosamine

  Covid-19 – laboratory analysis 1. RT PCR Detects the number of copies of viral gene Confirmatory test for COVID-19 2.TrueNat – Chip based real time PCR Used in remote areas with poor infrastructure Single step test for both screening & confirmation 3.LAMP test   the amplification is carried out at constant temperature In PCR  - amplification occurs with a series of alternating temperature steps or cycles . 4.Rapid Antigen Test Card based test which detects the presence of viral protein in swabs Good sensitivity but poor specificity 5.Serological Tests – lateral flow assays and ELISA For the detection of bodies   Particularly in patients who were infected & recovered  6.Biochemical Tests for Monitoring Cardiac biomarkers –  Troponin, NT-ProBNP, CK-MB,PT, myoglobin Hepatic biomarkers -  AST, ALT, GGT, LDH, Bilirubin Renal markers –  Blood Urea, Se.Creatinine Critical care markers –  Blood gases, electrolytes Routine urine biochemi...