Group C

1. Group C Wedyan Meshreky Helen Naguib Sharon Naguib

2. Part One • Ms DF recently diagnosed with leukaemia and is receiving L-asparaginase, amongst other cytotoxic agents. There have been a number of reports linking the use of L-asparaginase to diabetes mellitis. Explain..

3. Diabetes Mellitus • Serum glucose levels are regulated by absorption, cellular uptake, gluconeogenesis, glycogenolysis. • These processes are regulated by the pancreas, intestine, liver, kidneys and muscle. • Hyperglycaemia can result from disruption of the hormones involved in glucose regulation such as insulin or glucagon or from dysfunction of the organs involved in glucose homeostasis.

4. L-asparaginase • Anti-leukaemic agent used in combination with prednisone and vincristine for remission induction. • Malignant cells must acquire asparagine from surrounding fluid (such as blood) for protein synthesis whereas normal cells can synthesise their own asparagine.

5. Cont.. • Asparaginase is an enzyme derived from micro-organisms. • It deaminates asparagine to aspartic acid & ammonia in the plasma and ECF. • Therefore its deprives tumour cells of the AA asparagine for protein synthesis and so the cells die.

6. L-asparaginase & Diabetes • Hyperglycaemia is a well recognised side effect of therapy with L-asparaginase. • Hyperglycaemia & glycosuria without ketonemia occurs in 1-14% of patients treated with L-asparaginase, but is reversible upon discontinuation of the drug. • Insulin therapy is frequently required. • Hyperglycaemia can be worsened by the concurrent administration of high dose glucocorticoids in combination therapy.

7. Is the mechanism known? • Inhibition of insulin or insulin receptor synthesis leading to a combined insulin deficiency/resistance syndrome is the presumed mechanism. • It is unclear as to why L-asparaginase targets insulin, insulin receptors, thyroid binding protein and albumin synthesis but not other proteins such as glucagon.

8. Other mechanisms? • Another mechanism for the development of transient or permanent diabetes mellitus is pancreatitis which occurs in 1-2% of L-asparaginase treated patients. • Incidence of pancreatitis rises when L-asparaginase is combined with other cytotoxic agents.

9. Part two.. • L-asparaginase may affect other clinical chemistry parameters such as potassium and lipids. Please explain..

10. Hypertriglyceridemia • Parson’s et al observed an increase in fasting TG levels concluding it was due to an increase in endogenous synthesis of VLDLs • Apo-B100 is a major protein found in VLDLs increased levels detected suggesting an overproduction of VLDLs.

11. Hypertriglyceridemia… • Mechanism is unclear • Although the incidence of hypertriglyceridemia was 67%, this was found not to be associated with pancreatitis.

12. Hypercholesterolaemia • Changes in cholesterol levels not found to be related to treatment with l-asparaginase. • Most likely to be associated with the use of corticosteroids.

13. HDL • HDL levels in px’s with ALL found to be low • Decrease in HDL levels due to either • decreased formation, or • Increased removal from circulationlow HDL levels indicative of active cell proliferation

14. HDL… • During and after treatment with l-asparaginase HDL levels increased • Structural change in HDL particle from a high to a lower density particle • L-asparaginase decreases hepatic protein synthesis • Changes in lipid metabolism is reversible

15. Hyperkalaemia • TLS – release of intracellular contents leading to: hyperuricaemia, hyperphosphataemia, hypocalcaemia and hyperkalaemia. • Can lead to renal failure.

16. Hyperkalaemia… • Treatment: • Px should receive IV fluids (no K+) • Use of sodium bicarbonate, insulin or glucose can cause transcellular shift of K+ into muscle cells  decrease in K+ levels. • Monitor px for signs of hyperkalaemia

17. Part Three • Describe techniques used in the general monitoring of proteinuria and specifically, the measurement of albumin levels in urine

18. Dipstick Method • Semi-quantitative • Inexpensive • Takes less than 5 minutes to complete • Most common commercial method

19. Basic Principle • Uses a pH-dependent dye-buffer combination. • Paper spot impregnated with a citrate buffer, pH3 and a tetrabromphenol-blue indicator Relies on the ability of amino acid groups in proteins to bind and alter the colour of the acid-base indicators. • Most sensitive to Albumin because it contains the most amino groups.

20. YELLOW = NO PROTEIN GREEN =PROTEIN RESULTS

21. Interpretation of Results

22. False Positive results • Alkaline urine (pH>7.5) • Dipstick immersed for too long • Presence of penicillin, sulfonamides or tolbutamide • False Negative results • Dilute urine • Low molecular weight proteins • Non Albumin Proteins eg, Bence Jones Proteins .

23. The Sulfosalicylic Acid (SSA) Turbidity Test • Qualitative measure • Requires a few millilitres of freshly voided, centrifuged urine. • An equal amount of 3% SSA is added to the specimen • Acidification causes precipitation of protein in the sample. • Detects albumin, globulins and Bence-Jones proteins • In alkaline urine, it is a more accurate measure than the dipstick.

24. The turbidity of the suspension is proportional to the amount of protein precipitated • Amount of protein is also graded from 1 to 4