This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
As compared to unfractionated heparin, low molecular weight heparin - 
Select and explain. 
A. Are absorbed more uniformly when given subcutaneously, B. Require more frequent lab monitoring, C. Can be given to patients with heparin induced thrombocytopenia, D. A higher risk of osteopenia
A: Are absorbed more uniformly when given subcutaneously
Answer: A: Are absorbed more uniformly when given subcutaneously 
Explanation: Ans. is 'a' i.e., Are absorbed more uniformly when given subcutaneously o Unfractionated heparin binds to several plasma proteins, therefore it has less predictable dose-response profile when administered sc or iv. o On the other hand, LMW heparins are less protein bound and have a predictable dose response profile when administered sc or iv. About other options o Since aPTT/clotting time are not prolonged (much) with LMW heparins, laboratory monitoring is not needed. o LMW heparins are unsuitable for HIT as antibody may be cross-reactive. Agent of choice in HIT are direct thrombin inhibitors like hirudin, lepirudin, bivalirudin. o Osteoporosis (osteopenia) occurs as a dose related side effect of unfractionated heparin. The relative risk with LMW heparin is not yet estabilished.