H - Hour 
H - Hydrogen 
h - hypodermic 
H Chain - Heavy Chain 
H FLU - Haemophilus Influenza 
H&E - haematoxylin and eosin stains 
H&H - haemoglobin and haematocrit 
H&H - Hemoglobin and Hematocrit 
H&L - heart and lungs 
h&n - head and neck 
h&p - history and physical 
H.R. - House of Representatives bill 
h.s. - hour of sleep 
H/H - hemoglobin/hematocrit 
H/H - Henderson-Hasselbach 
H2 - histamine2 
HA - Headache 
haa - hepatitis associated antigen 
haa - hepatitis australian antigen 
HAA - hepatitis B surface antigen 
HAART - highly active antiretroviral t… 
HACCP - Hazard Analysis Critical Contr… 
HACE - High Altitude Cerebral Edema 
HAEM - Haematology 
HAI - haemagglutination-inhibition imm… 
HAPE - high-altitude pulmonary edema 
HASHD - hypertensive arteriosclerotic… 
HAT - Hypoxanthine, Aminopterin, & Thy… 
HAV - hepatitis A virus 
HAZCOM - Hazard Communication