Glossary

encephalitis – inflammation of the brain.

pulmonary – relating to the lungs.

amniocentesis – test in which cells around a fetus are removed and examined to detect genetic abnormalities

CD4 count – number of CD4 cells in a cubic millimetre of blood. CD4 counts results are given as a number that can be anywhere from 0 to over 2000 (rarely).

The range for an HIV-negative person is usually quoted as 430 – 1690. This means 95% of HIV negative people have a CD 4 count between 430 and 1690, but also that a few people have normal levels above or below this. A ‘normal’ CD4 count for an HIV positive person means getting above 500. However, this is an ideal goal and many people remain very well and healthy with CD4 counts that are lower than this.

Test results can also be reported in three main formats. ie a CD4 count of 350 can be written as:

• 350 cells/mm³ (cells per cubic millimetre); or
• 350 cells/μL (cells per microlitre); or
• 350 Χ 10⁶ cells/L (per million cells per litre: i.e.: times 10 to the power of 6, cells per litre)

See: Units of measure.

Since 2015, most treatment guidelines recommend starting treatment at any CD4 count, even when this is above 500.

Once viral load becomes undetectable on HIV treatment (ART), this also stops sexual transmission to HIV negative partners.

DEXA – a non-invasive scan that can measure the percentage of different body areas (whole body, trunk, right leg etc) that are muscle or fat. DEXA scans cannot determine if this is central fat (visceral adipose tissue, VAT) or sub-cutaneous fat (under the skin).

DEXA scan also can measure bone density and is used to monitor risk of osteopenia and osteoporosis.