H2O2 (hydrogen peroxide)

H2SO2 (sulfuric acid)

HA (hydroxyapatite)

HA (hemagglutinin)

HAA (hepatitis-associated antigen)

HAART (highly active antiretroviral therapy)

HAD (hospital anxiety and depression [scale])

HAGG (heat-aggregated IgG)

HAIR-AN (hyperandrogenism (HA), insulin resistance (IR) and acanthosis nigricans (AN))

HAL (hyperalimentation)