For 57+ female what are typical causes of mild anemia (Hb 10.6, RBC 3.6) & Thrombocytopenia (Pt 1.2 L) along with ~5% weight loss over 6-months?

Most common. is IRON DEFICIENCY but a complete work-up is ABSOLUTELY NECESSARY!.... This should include a GI evaluation and COMPLETE BLOOD analysis. (Iron , B-12-folic acid)....This should be done as soon as practicable! Hope this helps! Dr Z.
Recheck blood counts. It is not uncommon to see lab errors in the reported results. So it is always wise to recheck the blood counts once/twice more before you get worried or concerned. if the blood counts remain low, then a specialist(Hematologist) should be consulted to run more tests to find the cause/s. It is either reduced production of blood cells or loss of blood. For each possibility there are appropriate tests.