Which statement is false about low-molecular-weight heparins?

The statement that low-molecular-weight heparins (LMWH) require frequent monitoring of bleeding times is false. One of the advantages of LMWH compared to unfractionated heparin is that they typically do not require routine monitoring of anticoagulant effect through frequent blood tests. This is due to their predictable pharmacokinetics and pharmacodynamics, which allow for fixed dosing in many scenarios, thus simplifying patient management.

In contrast, unfractionated heparin requires close monitoring through activated partial thromboplastin time (aPTT) tests to ensure therapeutic levels and minimize the risk of bleeding or thrombosis, making the need for monitoring a key concern in its use.

The other statements regarding LMWH are true: they do have higher bioavailability compared to unfractionated heparin, which enhances their effectiveness; they possess a longer elimination half-life, allowing for less frequent dosing; and they are usually administered by subcutaneous injection, making them easier and more convenient for patients compared to intravenous administration often required with unfractionated heparin.