This combination is most concerning for melena due to gastrointestinal bleeding, usually from the upper gastrointestinal tract (esophagus, stomach, or duodenum), causing blood-loss anemia.

Common causes include:

At age 70, black tarry stool plus low hemoglobin/RBC count should be treated as a potentially serious bleed and needs urgent assessment today, preferably in an emergency department. Evaluation commonly includes vital signs, repeat complete blood count, kidney/liver and clotting tests, blood group and cross-match, rectal examination, and usually an upper endoscopy (gastroscopy) to locate and possibly treat the bleed. The textbook description supports that melena with anemia indicates gastrointestinal blood loss. Goldman-Cecil Medicine, “Gastrointestinal Hemorrhage”; Yamada’s Textbook of Gastroenterology, “Clinical manifestations.”

Call emergency services immediately if he has dizziness, fainting, weakness, shortness of breath, chest pain, rapid pulse, vomiting blood or coffee-ground material, confusion, or continuing large black stools.

Until assessed, do not use aspirin, ibuprofen, naproxen, diclofenac, or alcohol unless a clinician specifically directs otherwise. If he takes warfarin, apixaban, rivaroxaban, clopidogrel, aspirin, or another blood thinner, tell emergency staff immediately. Black stool can occasionally be due to iron tablets or bismuth, but anemia makes bleeding much more likely and it must not be assumed to be harmless. MedlinePlus guidance also identifies black/tarry stools as melena associated with gastrointestinal bleeding.