Tired all the time; heavy menses
Susan is a 44-year-old white female who presents with a complaint of being tired and having low energy. She is a G3P3 mother of a 15-year-old, a 13-year-old, and a 10-year- old. She is 5 feet tall and weighs 145 pounds. Her blood pressure is 116/78 mm Hg and her heart rate is 82. Past medical history is unremarkable except for a history of heavy menses, which Susan reports seem to be getting heavier. Her menses are regular and last 5 or 6 days. Her husband of 18 years had a vasectomy, so she does not use any hormonal birth control. Screening for depression is negative.
Susan gets regular exercise, mostly walking. She walks every weekend with her friends, usually a 6-to-8-mile walk. Susan is concerned because she is noticing that she is short of breath going up even small hills and needs to rest after she gets back from her walks.
Susan considers her diet well rounded. She has been trying to lose weight, so she has cut back on high-fat foods such as meat. She eats mostly fish and chicken for her protein.
She drinks two glasses of skim milk a day and eats a lot of salad to fill her up. Her salads are made with iceberg lettuce and tomatoes. She does not take any medications. She does not take a multivitamin.
Complete blood count (CBC) indicates a white blood cell (WBC) count of 9.6, red blood cell count (RBC) of 4.6, hemoglobin (Hgb) 11.1, hematocrit (Hct) 34%, mean corpuscular volume (MCV) 84, mean corpuscular hemoglobin concentration (MCHC) 31, and red blood cell distribution width (RDW) 14.5%, and platelets and WBC differential are unremarkable. Ferritin level is 13. Thyroid studies are within normal limits.
Briefly what follow-up laboratory would you draw?