Is d-dimer always elevated for disseminated intravascular coagulation (dic)?

Non specific - yes: D- dimer is degraded fibrin product, typically elevated in any condition that leads blood clot formation. In DIC, there is inappropriate cascade of coagulation in response to serious inflammation that leads to consumption of platelets to form clots in body organs. So d dimer elevation is used as one of the marker to help in making diagnosis of DIC. It is not specific for DIC.

Almost always: Hardly anything is 100%. D-dimer is elevated in DIC and other disorders e.g., deep vein thrombosis, and inflammation,