Management of HIV Infection

Introduction | The 'Good' HIV Patient | Interpreting Your Lab Results | Lab Test Tracker Chart | Viral Load Measurement

Introduction

Medical management of HIV infection is not an exact science - only because the virus presents itself differently in people who are infected with HIV - but there are certain accepted signs and symptoms any doctor should be aware of and respond to in order to successfully treat each patient.

Since HIV knowledge is constantly changing your doctor should keep up to date with these changes. Some doctors spend considerable amounts of personal time conducting research on specific illnesses associated with HIV infection - but there are some who do not. A doctor who was certified in 1998 may be 5 years out of date with existing treatment responses.

We are fortunate in Bermuda due to our small size because all doctors here belong to one governing body - the Bermuda Medical Association - and are required by law to report any incidences of HIV infection to the Department of Health & Family Services. Additionally all doctors on the island are required to be registered with the Government Registrar as a medical practitioner.

However part of good medical management is being a good patient. Doctors describe good patients as ones who take an active interest in their own health situations assuming some part of the responsibility in their own care and well-being.

The 'Good' HIV Patient

Reprinted from Good Doctors Good Patients Partners in HIV Treatment by Judith Rabkin Robert Remien and Christopher Wilson.

BACK TO TOP

Interpreting Your Lab Results (from Seattle Treatment Education Project - STEP) - June 1997

Note: 'Right Click' to download an Excel Sheet of the Lab Test Tracker Chart to track your Laboratory Tests. For help in putting your tests on the chart call AVSF office (in Bermuda) at 295-6882 or contact Seattle Treatment Education Project by calling (206) 329-4857. Non-commercial reproduction is encouraged. 

Also, you can download the following (Interpreting Your Lab Results) in MS Word format by clicking here.

A key to taking control of your health is learning to monitor your immune system. The bulk of immune monitoring is done through a variety of blood tests. Learning how to read and understand your laboratory tests can be quite frustrating. This article will provide basic information to help with this process. Because different labs reports results a little differently it may be wise to ask your doctor to help you read the results as well.

There are some basic rules which hold true for nearly all laboratory tests:

  1. Different laboratories can get different results from the same sample of blood. Make sure you ask your doctor which lab as used if it was noted on the report.

  2. Laboratories can make mistakes. If your results have changes dramatically since your last test have it run again.

  3. Most lab values have to be interpreted along with other clinical and laboratory data in order to develop a meaningful diagnosis. Very seldom will only one value give all of the answers.

  4. Laboratory values differ according to age sex current medications etc. Therefore the interpretation of these values needs to be done with these parameters in mind.

  5. The 'normal' range is the value that is normal for a person who does not have HIV infection. For example a low cholesterol value in an HIV positive individual is not uncommon.

COMPLETE BLOOD COUNT (CBC)

The complete blood count (CBC) is one of the most common tests offered by a doctor. It is a routine test used to evaluate the blood and general health. Asymptomatic HIV positive people should have this test done twice a year. Symptomatic people should have their CBC done at least every three months. Additionally if you are on anti-HIV medication you might have to have this test more often. A CBC measures all of the following parameters: red blood cell count (RBC) white blood cell count (WBC) hemoglobin hematocrit three red cell indices and the white cell differential. Platelet cunts are sometimes included in a CBC.

RED BLOOD CELL COUNT (RBC)

The RBC count is the number of red blood cells in a cubic millimeter of blood. The RBCs are the cells produced in the bone marrow that carry oxygen to your tissues. The normal rage is 4.5 - 5-9 million/mm3 for men and 4.0 - 5.3 million/mm3 for women. A slightly decreased value is not cause for alarm as many individuals with HIV have values below the normal range. However a markedly decreased value should be thoroughly investigated. A person with significant low RBC count can have symptoms of fatigue shortness of breath and appear pale in colour. A low RBC count can be due to progressive HIV illness or to certain medications or both. AZT for example can suppress the production of RBCs in some people. A decrease in the RBC count usually causes a decrease in the hemoglobin and hematocrit values.

WHITE BLOOD CELL COUNT (WBC)

The WBC count is the number of white blood cells in a cubic centimeter of blood. The primary function of these cells is to prevent and fight infections. There are many different types of white blood cells that play specific roles in fighting infections. These specific types of WBCs can be measured in a white cell differential. Normal WBC count is from 4 500 to 11 000. The WBC count can be decreased for a variety of reasons: certain medications decrease their production in the bone marrow minor viral infections which you may not even be aware of stress and opportunistic infections can all change WBC counts. Values markedly decrease should be cause for concern since during this situation one is more susceptible to other infections.

HEMOGLOBIN

Oxygen is carried to the tissues via hemoglobin in the red blood cells. A normal hemoglobin level is 14 - 18 g/dl for men and 12 - 16 g/dl for women. A slow progressive decline in hemoglobin is often seen in people with AIDS. This is usually due to a decline in the number of RBCs produced in the bone marrow. Any drug which causes a suppression of the bone marrow will decrease the hemoglobin levels. In most cases it's a matter of balancing the effects of the drug with it's potential side effects. When the side effects become too great either the drug must be discontinued or the dose reduced to a tolerable level. A drug which mimics the action of the hormone erythropoietin (a.k.a. Procrit EPO and newer brand names) has it's effect on the bone marrow causing the production of new RBCs. It has provided great relief to thousands of individuals of people with HIV and kidney dialysis patients. EPO has enabled many people to stay on bone marrow suppressive drugs without the need for transfusions.

HEMATOCRIT

The hematocrit is the percent of the cellular components in your blood to the fluid or blood plasma. This test is one of the truest markers of anemia. Normal values for men are 40-54% ad for women 37-47%. A decrease in hematocrit is always seen with a decrease in hemoglobin. These two values are linked to one another.

MEAN CELL VOLUME (MCV)

The mean cell volume or MCV is the most important of the RBC indices. It is a measure of the average size of the RBC. For those individuals taking AZT the MCV will always be normally elevated i.e. greater than 100. Vitamin B12 and Folic Acid deficiency also causes increases in MCV. Normal MCV levels are 80 - 96.

PLATELETS

Platelets are cellular fragments which are necessary for the blood to clot. When activated by trauma platelets migrate to the site of injury where they become 'sticky' - adhering to the injured site and helping to form a fibrin clot or scab. Normal platelet values are 150 000 - 450 000. In some individuals HIV itself causes a decrease in the number of platelets. Otherwise drugs can also cause low platelet counts. Even though counts are considered low below 150 000 most people can survive without the threat of internal bleeding with counts above 50 000. On very rare occasions the number of platelets present are adequate but for unknown reasons they don't function correctly. Any malady involving one's platelets can be a potentially serious condition.

WHITE CELL DIFFERENTIAL

The white cell differential counts 100 white cells and differentiates them by type. This gives a percent of the different kinds of white cells in relation to one another. The three main types are: polymorphonuclear cells (PMNs) lymphocytes and monocytes. PMNs are increased during bacteria infections while lymphocytes are decreased with viral infections. Increased monocytes are sometimes seen in chronic infections. Normal percent of PMNs is 55 - 80%. 25 - 45% is the normal number of lymphocytes and 2 - 10% is normal for monocytes.

There are a wide range of blood chemistry tests which are done on individuals either routinely or for specific reasons. Some of the ones pertaining to HIV are mentioned below.

CHOLESTEROL

Cholesterol levels as mentioned earlier are routinely decreased in HIV positive individuals. It's not understood why this occurs but it is thought to be related to altered metabolism. Normal cholesterol levels are 150 - 250 mg/dl.

AMYLASE

Amylase is an enzyme that is secreted in the mouth by the salivary glands and also in the pancreas. It can be an early warning sign of acute pancreatitis when elevated. ddI can cause problems with the pancreas in a small number of people taking the drug. Normal amylase levels are 25 - 125 milliunits/ml.

CPK or CK

CPK or CK is an enzyme that's found in the brain and muscles of the body. Strenuous exercise as well as heart attack can cause increases in CPK. This makes clear the point of elevating an abnormal test result in the context of other factors. Myopathy dysfunction/distress with the muscles can sometimes be confirmed with an elevated CPK. Myopathy is usually caused by HIV but can also b due to AZT especially at higher dosages. Normal levels of this enzyme are 1 - 80 milliunits/ml (30 degrees0 or 55 - 170 milliunits/ml (37 degrees). Values will be slightly lower for women.

LIVER FUNCTION TESTS

Liver function tests include 5 - 6 individual tests which collectively can help determine the status of ones liver. Elevated liver enzymes are most often caused by certain medications. The HIV positive population also has a high prevalence of hepatitis. At least 4 different viruses are known to cause hepatitis all leading to increased liver function tests. Therefore compound factors can be at work. If liver enzymes are only moderately elevated most doctors will take a 'wait and see' attitude monitoring them over a period of a few weeks to a few months. However if elevation is quite high the underlying factor must be found. This might very well be one of the medications that you are currently taking. The names of these liver function tests include SGOT SGPT alkaline phos total bilirubin and LDH.

KIDNEY FUNCTION TESTS

Two tests which measure kidney function are the BUN and Creatinine. The usefulness of these two tests in an HIV positive individual usually relates to medications possibly toxic o the kidneys. Hence kidney function is monitored in this way. Foscarnet is an example of a drug which can cause renal toxicity. Normal BUN levels are 10 - 20 mg/dl. Normal levels of Creatinine are 0.6 - 1.1 mg/dl.

LYMPHOCYTE SUBSETS

The category of lymphocyte subsets includes absolute counts and percentages of CD4 and CD8 cells as well as other parameters. Usually the number and percent of B cells is included and the number and percent of all lymphocytes (except those called 'natural killer' or NK cells). Lymphocytes are broken down mainly into CD4(+) cell and CD8(+) cells. It is well known that HIV causes a slow progressive decline in the number and percent of CD4(+) cells in most individuals. There are exceptions. Some people progress in their disease rapidly and others don't seem to progress much at all after more than 12 or 13 years. normal CD4 counts are 350 - 1500. The role of CD8 cells is less clearly understood. Early on in the epidemic high CD8 cell counts caused inversion of the CD4:CD8 ratio and was thought to adversely affect illness. Now it is generally believed that elevated CD8 counts are advantageous since it's thought to keep HIV somewhat constrained. Normal CD8 cell counts in an HIV negative person is 275 - 780.

BACK TO TOP

Viral Load Measurement & Math

Viral load monitoring can establish the patient's prognosis in HIV infection. Rising viral load indicate disease progression; falling viral load, a favourable prognostic trend.

Plasma viral load may range from a few hundred virions (viral copies, or viral equivalents) o >1,000,000 per ml, a 10,000-fold range. Such large ranges are easiest to express in logarithms (logs).

To express a number in logarithmic form, a base is raised to a power. he latter is the logarithm, or exponent. The base 10 is commonly used in medicine without being explicitly specified; often only the power (the exponent, or log) is shown. A viral load of 10,000 copies/ml, or 100,000 copies/ml, is 105 copies/ml, or 5 logs.

Changes in viral load are commonly expressed in either numerical or logarithmic terms. For example, a twofold change is equal to approximately a 0.3-log change.

In viral load measurements, the sum of laboratory and biological variation is generally assumed to be 0.3 to 0.5 log (twofold to threefold). Therefore, only changes greater that this are considered meaningful.

Viral loads below 50 copies/ml may not be detectable with current assays however, the patient should be aware that he or she still has the virus present and therefore, can still transmit the virus during unprotected sexual activity.