Monitoring Hiv Rna in Children

Quantitative HIV RNA assays can be obtained to assess the numbers of copies of RNA and, indirectly, the virion level or viral burden. A balance is reached in HIV-infected individuals between 6 and 12 months following acute infections, such that there is a steady state of on-going viral production and immune elimination/replacement.4041 Plasma HIV-1 RNA levels increase rapidly after birth, peak at 1 -2 months of age (median values at 1 and 2 months, 318,000 and 256,000 copies/ml, respectively), and then slowly decline to a median of 34,000 copies/ml at 24 months.7 Adult levels are reached by age 6 years. Extreme levels of HIV RNA (300,000 copies/ml) correlate with disease progression and death within the first 12 months of life. Levels during the first year of life are associated with a 54% reduction in progression for each logw reduction in HlV RNA level. Baseline as well as changes in HIV RNA copy number and CD4 lymphocyte percentage over time independently predict mortality in infected children. The use of the two markers together more accurately defines prognosis.2542-44 It is impor-

tant to note that the absolute HIV RNA copy number obtained from a single specimen tested by two different assays can differ as much as twofold (0.3 log,,,); therefore, a single assay method should be chosen and consistently used for individual patient monitoring. Assays currently available include the Amplicor Monitor (Roche Diagnostics Systems, Branchburg, NJ), the branch-chain DNA assay (Quantiplex, Chiron Corporation, Emeryville, CA), and plasma RNA measure by nucleic acid sequence-based amplification (Organon Technike, Durham, NC). Initiation of antiretroviral therapy and alteration of therapy should ideally be based on two RNA measurements.

The virological course and immunopathogenesis of HIV during adolescence are not clearly defined. Older adolescents should be treated similarly to adults.9 Antiretroviral medications and prophylactic medications for op portunistic infection prophylaxis are prescribed according to Tanner staging rather than age.45

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