Clinical biochemistry

1. Clinical biochemistry Dr ShahidaMushtaq

2. What is clinical biochemistry • Clinical chemistry, chemical pathology and medical biochemistry • is the area of clinical pathology that is generally concerned with analysis of bodily fluids. • Originated in the 19th century with simple chemistry test of blood and urine

3. Course contents • Disorders of Protein Metabolism: • Non-protein nitrogenous compounds (Urea, uric acid & amino acids): 3 lectures • Their normal plasma levels • Disease states associated with their increased and decreased levels in the plasma. • Plasma Proteins: • Normal and abnormal levels of plasma proteins and diseases associated with increased and decreased levels. • Immunochemistry • Components of the immune system.

4. Course contents (cont) Diseases associated with disorders in the immune system, multiple myeloma, systemic lupus erythromatosis, heavy-chain diseases, macroglobulinemia etc. • Clinical Enzymology • Changes in enzymatic activity in disease states • Hemoglobin • Normal and types of abnormal hemoglobins. • Pathological cases associated with abnormal hemoglobin, e.g., thalassemia, sickle cell anemia etc.

5. Course contents (cont) • Disorders of Lipid Metabolism • Hyper and hypolipoproteinemia. • Atherosclerosis & lipidoses. • Fatty liver • Disorders of Electrolytes, Blood Gases &Acid-base Balance • Sodium, potassium, chloride & their diagnostic value. • Gas transport in the blood (Oxygen & CO2). • Blood pH and its regulation. • Acidosis and alkalosis (Metabolic and respiratory) & Pathological conditions associated with each condition.

6. Lab Work • Blood analysis: • Electrophoretic separation of plasma proteins. • Electrophoretic separation of plasma lipoproteins. • Estimation of serum enzymes: • LDH and its isoenzymes. • CPK and its isoenzymes. • Ornithinecarbamoyltransferase. • 5-nucleotidase. • Isocitricdehydrogenase. • Sorbitoldehydrogenase. • Glucose-6-P dehydrogenase. • Aldolase • Leucineaminopeptidase. • Aspartate and AlanineAminotransferases AST and ALT.

7. Lab Work • Serum electrolytes: • Chloride sodium, Potassium, Calcium, Magnesium, Phosphorus. • Urine Analysis: • Porphyrins. • Urobilinogen, Amino Levulinic Acid (ALA)

8. Recommended Books • Clinical Biochemistry, 2nd Edition, 2008, R. Luxton. • Clinical Biochemistry made ridiculously simple, 2010, Stephen Goldberg. • Clinical Biochemistry; An illustrated color text, 2008, Allan Gaw, Michael J. Murphy, Robert A.

9. Protein metabolic disorders(inborn errors of metabolism)

10. A Clinically Useful Classification • Group 1: Disorders that give rise to Intoxication • Group 2: Disorders involving energy metabolism. • Group 3: Disorders involving complex molecules. (Proposed by JM Saudubray-2002)

11. Group 1: Intoxication Type This group includes IEM that lead to acute or progressive intoxication from accumulation of toxic compounds proximal to metabolic block.

12. Group 1: Intoxication Type (Cont) Includes (Cont): • Congenital Urea Cycle Defects • Arginosuccinate Lyase Def • Ornithine Carbamyl Transferase Def • Sugar Intolerance • Galactosaemia • Hereditary Fructose Intolerance

13. Group 1: Intoxication Type (Cont) Includes: • Aminoacidopathiese.g: • Phenylketoneuria (PKU) • Maple Syrup Urine Disease (MSUD) • Tyrosinaemia type I • Organic acidaemias e.g. • Methylmalonicacidaemia (MMA) • PropionicAcidaemia • IsovalericAcidaemia

14. GROUP 2: DEFECTS IN ENEREGY METABOLISM This group consists of IEM with symptoms due at least partly to a deficiency of energy production or utilization. They result from a defect in the: • Liver • Myocardium • Brain • Muscle

15. GROUP 2: DEFECTS IN ENEREGY METABOLISM (Cont) Includes: • Hypoglycaemic disorders • Gluconeogenesis defects • Glycogenosis defects • Hyperinsulinism • Fatty Acid Oxidation Disorders

16. GROUP 2: DEFECTS IN ENEREGY METABOLISM (Cont) Includes (Cont) • Congenital Lactic Acidaemias • Pyruvate carboxylase deficiency • Krebs Citric Cycle defects • Mitochondrial Respiratory Chain defects

17. GROUP 3: DISORDERS INVOLVING COMPLEX MOLECULES This group includes diseases that involve defects in the synthesis or the catabolism of complex molecules. These diseases are: • Progressive • Permanent • Independent of intercurrent events • Not amenable to treatment.

18. GROUP 3: DISORDERS INVOLVING COMPLEX MOLECULES(Cont) Includes: • Lysosomal Disorders • Peroxisomal Disorders • Golgi Apparatus Disorders • Inborn Errors of Cholesterol Synthesis

19. IEM on the basis of affected enzyme or protein • Carbohydrate metabolism • Glycogen storage diseases various • Galactosemia galactose-1-phosphate uridyletransferase, galactosekinase • Hereditary fructose intolerance fructose bisphosphatealdolase • Amino acid metabolism • Phenylketonuria phenylalanine hydroxylase • Alkaptonuriahomogentisic acid oxidase • Maple syrup urine disease branched chain ketoacidhydroxylase

20. Lipid metabolism • Hyper and hypo lipoproteinemia various • Steroid metabolism • Congenital adrenal hyperplasia 21-hydroxylase • Purine metabolism • Gout various • Lesch-Nyhan syndrome HGPRT (hypoxanthine-guanine phosphoribosyltransferase)

21. Lysosomal storage disease • Tay-sachs disease…….. hexosaminidase A • Gaucher’s disease…….. glycosylceramidase • Cell transport defects • Cystinuria………. amino acid transport • Renal glycosuria………. glucose transport • Renal tubular acidosis…. hydrogen ion transport

22. Some facts • About 5 million children die in the first month of life in developing countries • Four million children are born with some congenital anomaly. WHO

23. The baby –Some facts (cont) • Almost 27 - 30 % of babies dying of SIDS are now proved to be having some Inborn Errors of Metabolism (IEM). • About 5 to 15 % of all sick neonates in NICU are expected to have some IEM WHO

24. IEM • a single gene defect causes a clinically significant block in a metabolic pathway resulting either in accumulation of substrate behind the block or deficiency of the product

26. IEM arises from a damaged gene which leads to abnormal enzyme. • May be autosomal or sex-linked. • May be recessive or dominant in expression. • Heterozygote will have both normal and abnormal alleles. But homozygote will have two alleles the same on each chromosome.

27. Investigations • An accumulation of the substrate before the enzyme defect*. • A decrease in the amount of the product is observed. • An increased concentration of the alternative metabolites*. • A decrease or absence of the enzyme activity.

28. Investigations • Screening for IEM who do not have the symptoms • Investigations of the patient with symptoms of the IEM

29. Screening of newborn

30. Laboratory Diagnosis of IEM May be carried out in three stages: • Diagnosis of Broad Category: Saudubrayet al (2002)* suggested a battery of simple and routine tests for identification of the broad category of the disorders. These tests include plasma electrolytes, ABGs, blood ammonia and lactic acid etc. *Saudubray JM, Nasoogne MC, Lonlay PD, Touati G. Clinical approach to inherited metabolic disorders in neonates: an overview. SminNeonatol 2002; 7: 3-15.

31. Laboratory Diagnosis of IEM (cont) May be carried out in three stages: b. Diagnosis of the exact disorder • It requires very sophisticated equipment e.g. HPLC, tandem mass spectrometry, GC-MS and ion exchange chromatography.

32. Laboratory Diagnosis of IEM (Cont) May be carried out in three stages: b. Diagnosis of the exact disorder (cont) • These techniques also require elaborate infrastructure of trained manpower, proper back-up service for the instruments and regular supply of reagents.

33. Laboratory Diagnosis of IEM May be carried out in three stages: b. Diagnosis of the exact disorder (cont) • AKU hospital has taken an initiative to establish the first-ever lab in the country for the pin-point diagnosis of some of the IEM.

34. Laboratory Diagnosis of IEM (Cont) May be carried out in three stages: c. Determination of deficient enzyme or proteinAlthough a few laboratories in the world provide this facility, this is only of academic and research interest. Diagnosis of the genetic defect provides another promising pathway for some of these disorders.