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Clinical biochemistry

Clinical biochemistry. Dr Shahida Mushtaq. Objectives. provides advanced understanding and applied knowledge in the theory and practice of Clinical Biochemistry a critical understanding of how biochemical investigations are employed to develop a clinical diagnosis

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Clinical biochemistry

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  1. Clinical biochemistry Dr ShahidaMushtaq

  2. Objectives • provides advanced understanding and applied knowledge in the theory and practice of Clinical Biochemistry • a critical understanding of how biochemical investigations are employed to develop a clinical diagnosis • Help you in developing necessary professional and research skills to promote lifelong learning and career development

  3. Course Contents: • Disorders of Protein Metabolism: • Non-protein nitrogenous compounds (Urea, uric acid & amino acids): • 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. • Diseases associated with disorders in the immune system, multiple myeloma, systemic lupus erythromatosis, heavy-chain diseases, macroglobulinemia etc.

  4. 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. • Disorders of Lipid Metabolism • Hyper and hypolipoproteinemia. • Atherosclerosis & lipidoses. • Fatty liver.

  5. 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 • Estimation of serum enzymes: • LDH and its isoenzymes. • CPK and its isoenzymes. • Aldolase • Leucineaminopeptidase. • Aspartate and AlanineAminotransferases AST and ALT. • Serum glucose • Lipid profile

  7. Reference books • Clinical Biochemistry, 2nd Edition, 2008, R. Luxton.

  8. Inborn errors of metabolism • They arise from damaged gene leading to an abnormal enzyme. • They can affect many different biochemical pathways. • May be autosomal or sex linked. • Mutation in gametes and normal cells.

  9. IBEM • They involve inheritance of abnormal gene from one or both parents and are linked with abnormal enzyme leading to defect in metabolic pathway. • There may be defects in other types of proteins for example cystic fibrosis.

  10. Inborn Error Of Metabolism (IEM) • About 1300 diseases known so far. • About 100 start in the neonatal period • About 20 are amenable to treatment Incidence: • rare

  11. GENERAL ASPECTS of (IEM) • Suspect IEM in parallel to other common conditions e.g. Sepsis. • Non-specific signs and symptoms e.g. poor feeding, lethargy, failure to thrive. • Majority of cases may be sporadic. • Inborn errors of intoxication are usually amenable to treatment.

  12. 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)

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

  14. Group 1: Intoxication Type (Cont) Includes: • Aminoacidopathies e.g: • Phenylketoneuria (PKU) • Maple Syrup Urine Disease (MSUD) • Tyrosinaemia type I • Organic acidaemias e.g. • Methylmalonic acidaemia (MMA) • Propionic Acidaemia • Isovaleric Acidaemia

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

  16. 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

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

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

  19. 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.

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

  21. inheritance • 23 pairs of chromosomes • Autosomal or sex linked • Homozygous or heterozygous • inheritance pattern is different for both autosomal or sex linked genes. • Expression of gene depends on dominence of genes.

  22. INVESTIGATION OF IBEM • An accumulation of the sustrate before enzyme defect. • Decrease in amount of product of enzyme. • An increased concentration of alternate metabolism • A decrease or absence of enzyme activity

  23. INVESTIGATION OF IBEM • Screening for the IBEM in individuals who do not have symptoms. • Investigations of the patients with symptoms of the IBEM.

  24. Screening • Detecting a patient with an IBEM even before he shows overt symptoms of the disease • Screening should be done for high risk group • All newborn infants • Family of affected children • Expectant mothers who have previously had affected children (pre natal diagnosis)

  25. Screening of newborn infants • There is suitable treatment available for the disease • The disease is life threatening or seriously debelitating • The disease has relatively high incidence • A suitable test is available • The cost is acceptable. • PHENYLKETONURIA AND CONGENITAL HYPOTHYROIDISM

  26. Investigation of suspected IBEM • Infant may present with symptoms within few days after birth or within few weeks of life. • Failure to thrive • Poor feeding • Persistent vomiting • Unexplained jaundice • Unexplained hypoglycemia • Ketosis • Lactic acidosis • Convulsions and coma • Lethargy • Hypotonia • hyperventilation

  27. Front line tests • Plasma • Electrolytes • Acid base balance • Blood gases • Glucose • LFT • Calcium

  28. Follow up test • Plasma • Insulin • lactic acid • Ammonia • ketones • Urine • Amino acid • Sugar • Organic acids

  29. Prenatal diagnosis • Parents of the affected children • Amniocentesis • Fibroblasts recovered from amniotic fluid • Cultured and specific enzyme studies are performed • 15th week should be completed by 20th week • CVS • 9th week complete within 10 days • DNA analysis • Cystic fibrosis

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