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Tests and monitoring in HIV infection

UK standard of care and some other useful tests Matthew Williams UK CAB. Tests and monitoring in HIV infection. UK standard of care and some other useful tests. Tests and monitoring in HIV infection. CD4 count Viral load Resistance Therapeutic drug monitoring.

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Tests and monitoring in HIV infection

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  1. UK standard of care and some other useful tests Matthew Williams UK CAB Tests and monitoring in HIV infection

  2. UK standard of care and some other useful tests Tests and monitoring in HIV infection

  3. CD4 count Viral load Resistance Therapeutic drug monitoring Tests and monitoring in HIV infection

  4. CD4 count Blood test Used to judge how far HIV disease has advanced Helps predict the risk of opportunistic infections Most useful when it is compared with the count obtained from an earlier test. Tests and monitoring in HIV infection

  5. CD4 count CD4 dips on HIV infection from a normal count of 500-1,500 cells in a cubic millimeter (mm3) of blood (a drop, more or less), recovers somewhat, then falls over time down to as low as 0. Tests and monitoring in HIV infection

  6. CD4 count CD4 <200 = greater risk of opportunistic infections (OIs) = “AIDS” = threshold for prophylaxis eg for PCP = bottom of UK threshold for starting combination therapy CD4 <50 = very great risk of OIs Tests and monitoring in HIV infection

  7. CD4 count CD4 over 350: treatment not recommended CD4 any count: treatment recommended if “symptomatic” BHIVA, Treatment of HIV-infected adults with antiretroviral therapy (2006) Tests and monitoring in HIV infection

  8. CD4 count CD4 count lower in pregnancy – temporary drop of 50 cells/mm3 Tests and monitoring in HIV infection

  9. CD4 count CD4% - CD4 cells as proportion of all lymphocytes (white blood cells), normally about 40% in adults CD4% is used to monitor babies and children who have higher CD4 counts Tests and monitoring in HIV infection

  10. Viral load Blood test (can be other serum eg CSF) Used to judge whether treatment is working (early infection?) Helps predict the risk of disease progression? Most useful when it is compared with the count obtained from an earlier test. Tests and monitoring in HIV infection

  11. Viral load After infection, viral load surges to a very high for the first weeks or months Often 1,000,000+ copies in a millilitre (mL) of blood, when you are very infectious Viral load falls as the body controls HIV infection then rises over time as immunity is damaged Tests and monitoring in HIV infection

  12. Viral load When you are on HIV treatment, your viral load should be reduced to “undetectable” = <50 copies/mL = 1.7 log10 Tests and monitoring in HIV infection

  13. Viral load Blip = 1 viral load test detectable (over 50 copies) – 2 of these may be a trend and indicate “virological failure” Tests and monitoring in HIV infection

  14. Viral load Viral load is usually a PCR (polymerase chain reaction) quantitative (counting) test for HIV RNA - research tests can measure viral load below 50 copies Other tests: bDNA (branched DNA), NASBA (nucleic acid sequence based amplification) Tests and monitoring in HIV infection

  15. Resistance test Blood test (can be other serum eg CSF) Used to judge whether treatment will work Involves interpretation Two types: genotype and phenotype Viral load needs to be over 500 copies/mL for the test to work Tests and monitoring in HIV infection

  16. Resistance test Tests and monitoring in HIV infection • Resistance test

  17. Resistance test Genotype looks at genetic make up of HIV viruses in infection and compares this to what is known about which mutations lead to resistance Phenotype looks at whether the drugs work in a test tube Tests and monitoring in HIV infection

  18. Resistance test Minority species of resistant virus may be missed by conventional resistance testing (ie if less than 10% of your virus is resistant the test may not pick this up). In patients without evidence of transmitted resistance, a suboptimal virological response to first-line therapy (<1 log10 copies/mL drop in viral load by 4–8 weeks) should prompt resistance testing at that time. BHIVA, Treatment of HIV-infected adults with antiretroviral therapy (2006) Tests and monitoring in HIV infection

  19. Resistance test Tests and monitoring in HIV infection

  20. Therapeutic drug monitoring (TDM) Measures drug levels in the blood - requires blood samples at recorded time intervals after a drug dose Practical uses for NNRTIs and PIs Tests and monitoring in HIV infection

  21. Therapeutic drug monitoring (TDM) Freely available at low (£45/drug) or no cost (if covered by drug company) from University of Liverpool Department of Pharmacology. http://www.hiv-druginteractions.org/ http://www.delphicdiagnostics.com/ Tests and monitoring in HIV infection

  22. Therapeutic drug monitoring (TDM) Drug levels vary – much evidence of this – recommended dose is based on averages University of Liverpool TDM audit – 20-25% of children on NNRTIs or PIs using drugs below therapeutic level. http://www.i-base.info/htb/v7/htb7-6/University.html Tests and monitoring in HIV infection

  23. UK standard of care (BHIVA) All patients should have: i) a resistance test at diagnosis, ii) before starting HAART, iii) if viral load does not drop by <1log10 after 4-8 weeks after starting HAART, (genotype) iv) after virological failure Tests and monitoring in HIV infection

  24. UK standard of care BHIVA – viral load before and 4-8 weeks after starting treatment (as necessary thereafter) Tests and monitoring in HIV infection

  25. UK standard of care BHIVA – CD4 count before treatment (as necessary thereafter) Tests and monitoring in HIV infection

  26. UK standard of care BHIVA – TDM for management of drug interactions, pregnancy and paediatrics, highly treatment-experienced patients when TDM and resistance test results can be integrated, kidney or liver impairment, transplant patients, drug toxicity, alternative dosing where safety and efficacy has not been established Tests and monitoring in HIV infection

  27. UK standard of care and some other useful tests Tests and monitoring in HIV infection

  28. Liver enzymes Kidney function Urine Albumin Bone density Glucose Platelets Red blood count White blood count Lipids Tests and monitoring in HIV infection

  29. C-reactive protein DEXA scan Chest x-ray Sputum serology Lactic acid and blood pH Haemoglobin and iron Serum urea Creatine phosphokinase and lactate dehydrogenase Electrolytes Tests and monitoring in HIV infection

  30. Tests = blood, blood and more blood... Many tests require a blood sample Tests and monitoring in HIV infection

  31. Blood glucose Blood cholesterols and triglycerides Kidney function C-reactive protein Liver enzymes Anaemia Lactic acidosis Tests and monitoring in HIV infection

  32. Blood glucose Normal range 4-8 millimoles per litre (µmol/L) High glucose ?= kidney disease, neuropathy, insulin resistance, cardiovascular disease Drugs: PIs, tenofovir, AZT? Tests and monitoring in HIV infection

  33. Blood cholesterols and triglycerides Low-density lipoproteins (LDLs) or "bad" cholesterol, and high-density lipoproteins (HDLs) or "good" cholesterol – ratio is key measure Insulin resistance, metabolic syndrome, cardiovascular disease Drugs: PIs, AZT, efavirenz Tests and monitoring in HIV infection

  34. Blood cholesterols and triglycerides Total cholesterol Target level under 5.2 µmol/L (4-6.4 µmol/L) Tests and monitoring in HIV infection

  35. Blood cholesterols and triglycerides LDL cholesterol Target level under 3.4 µmol/L Tests and monitoring in HIV infection

  36. Blood cholesterols and triglycerides HDL cholesterol Target level over 0.9 µmol/L Tests and monitoring in HIV infection

  37. Blood cholesterols and triglycerides Cholesterol – CV risk cannot be judged on cholesterol levels alone, HDL:LDL ratio, lifestyle, BMI, age and other factors are important Smoking! Tests and monitoring in HIV infection

  38. Blood cholesterols and triglycerides Triglycerides Fasted levels <2.2 µmol/L normal, 2.2–4.4 µmol/l borderline, >11 µmol/L very high Each +1.1 µmol/L increased the risk of a heart attack by about 25% in men and 60% in women Tests and monitoring in HIV infection

  39. Urine Dipstick test Protein – kidney (tenofovir) << mostly albumin Glucose – insulin resistance (PIs), kidney (tenofovir, indinavir?, atazanavir?) Bilirubin – liver ( X atazanavir) Sensitive but not specific Tests and monitoring in HIV infection

  40. Kidney function Urine dipstick test or blood test = first test and is indicative but inconclusive Tests and monitoring in HIV infection

  41. Kidney function Serum creatinine (blood, not very specific or sensitive) Creatinine clearance (blood and/or urine samples over 24 hours) Calculated creatinine clearance (1 blood sample) – also called estimated glomular filtration rate (eGFR) Creatinine clearance can increase in pregnancy Tests and monitoring in HIV infection

  42. Kidney function Different formulas to calculate GFR http://en.wikipedia.org/wiki/Glomerular_filtration_rate Tests and monitoring in HIV infection

  43. C-reactive protein Risk of diabetes, hypertension and CV disease Low risk: <1mg/L High risk: >3mg/L Drugs: PIs?, AZT? C-reactive protein is a plasma protein produced by the liver (so, another blood test...) Tests and monitoring in HIV infection

  44. C-reactive protein C-reactive protein is also marker of inflammation from infection but seems to be a reliable marker for CV disease in HIV regardless of HAART http://gateway.nlm.nih.gov/MeetingAbstracts/102261383.html Tests and monitoring in HIV infection

  45. Liver enzymes AST, ALT, ALP, GGT and bilirubin Many conditions, some specific indications, complicated by hepatitis B and C coinfection, pharmacological agents (all kinds) and food Drugs: ritonavir, nevirapine, efavirenz, tipranavir, atazanavir, indinavir, d4T - most ARVS and many other drugs may affect the liver Tests and monitoring in HIV infection

  46. Liver enzymes ALT (alanine aminotransferase) Normal range 7-30 units/L W, 10-55 units/L M May be more reliable sign of liver damage Tests and monitoring in HIV infection

  47. Liver enzymes AST (aspartate aminotransferase) Normal range 9-25 units/L W, 10-40 units/L M Unreliable sign of liver damage Pregnancy may decrease AST Tests and monitoring in HIV infection

  48. Liver enzymes ALP (alkaline phosphatase) Normal range 30-100 units/L W, 45-115 units/L M Non-specific sign of liver damage Atazanavir and indinavir can raise ALP Tests and monitoring in HIV infection

  49. Liver enzymes GGT (gamma glutamyl transferase) Normal range >50 units/L W, >65 units/L M Can be specific sign of liver damage Tests and monitoring in HIV infection

  50. Liver enzymes Interpretation requires experience and the whole picture ALP+ GGT normal = bone disease? ALP+ GGT+ = bile ducts? liver damage? 10 x ALT/AST = viral hepatitis? ARVs? Tests and monitoring in HIV infection

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