Eligible patients will be recruited from either Stanford Hospital and Clinics (SHC) or the Veterans Affairs Palo Alto Health Care System (VAPAHCS).

Evaluation for anemia will include a complete blood count, reticulocyte count, careful review of the peripheral smear, evaluation for nutrient deficiencies (iron, B12 and folate), and renal and thyroid dysfunction, with additional evaluation dependent on initial findings. Patients will be categorized according to the etiology of the anemia.

In addition, all subjects who consent to do so will have the following additional research tests done: 40 mL of urine for urinary creatinine and urinary hepcidin; and 35 cc of blood drawn for serum soluble transferrin receptor (if not already done), C-reactive protein, erythrocyte sedimentation rate, D-Dimer, and a cytokine profile including IL-6 level by ELISA and/or IL-1, IL-6, TNF-alpha, VEGF levels which will be run by multiplex assay or other immunologic methods.

In addition (except for VAPAHCS subjects), 20-30 cc will be drawn for tissue banking serum, plasma and nucleated peripheral blood cells for possible DNA and other analyses in the future.

A subset of subjects (approximately 6-30 subjects with anemia of chronic inflammation, and 6-30 subjects with unexplained anemia) will have bone marrow aspiration and biopsy specimens obtained. Aspirate and biopsy specimens will also be obtained if clinically indicated to determine the etiology of the anemia (i.e. to evaluate for myelodysplastic syndrome).

59 elderly (> 65 years of age) non-anemic participants will be enrolled as elderly healthy controls for blood and urine samples; 6-30 of these will be recruited for a bone marrow aspirate and biopsy; 59 young (20-64 years of age) non-anemic participants will be enrolled as young healthy controls (without bone marrow studies), 6-10 bone marrow samples from young healthy controls will be purchased from an outside vendor.

Inclusion Criteria:ELDERLY ANEMIC:

Aged 65 or older Hemoglobin < 13 g/dL (in men) and < 12 g/dL (in women) on at least 2 occasions, 30 days apart, with the most recent value within at least 14 days of enrollment into the study. In addition, if a CBC is drawn on the date of enrollment, hemoglobin must meet eligibility criteria in order for the patient to enroll.

Outpatient at either the VAPAHCS or SHC Independent/community living Written informed consent obtained Performance level ECOG 2 or better

NON-ANEMIC ELDERLY CONTROL POPULATION FOR BLOOD, URINE AND BONE MARROW SAMPLES:

Age 65 or older Hemoglobin >= 13 g/dL (in men) or >= 12 g/dL (in women) within at least 30 days of enrollment into the study.

Normal white blood cell and platelet counts Outpatient at either VAPAHCS or SHC Independent/ community living Written informed consent obtained Performance level ECOG 2 or better Matched to UA population by gender and 10 year age strata (65 to < 75, 75 to < 85, 85 or older)

NON-ANEMIC YOUNG CONTROL POPULATION FOR BLOOD AND URINE SAMPLES:

Age 20-64 Hemoglobin >= 13 g/dL (in men) or >= 12 g/dL (in women) within at least 30 days of enrollment into the study.

Normal white blood cell and platelet counts Outpatient at either VAPAHCS or SHC Independent/community living Written informed consent obtained Performance level ECOG 2 or better Will be recruited by the following age strata: 20 to < 35, 35 to < 50, 50 to < 65

NON-ANEMIC YOUNG CONTROL POPULATION FOR BONE MARROW (these samples will be purchased):

Age 20-35

Hemoglobin >= 13 g/dL in men, >= 12 g/dL in women as obtained by procurement company. Exclusion Criteria:For all groups:

Substance abuse or mental health problems that would make compliance with the protocol unlikely.

Predicted mortality based on co-morbidities of less than 3 months. Known diagnosis of bone marrow disorder including leukemia, metastatic malignancy with bone marrow involvement or myelodysplastic syndrome or MGUS.

On any erythropoiesis-stimulating agents in the prior 3 months. History of red blood cell transfusion in the prior 3 months. End stage liver disease defined by the participant's providers End stage renal disease on hemodialysis. Known significant bleeding or other disorder which would make phlebotomy or bone marrow aspirate/ biopsy significantly risky.

On any other study wtih ongoing phlebotomy or marrow donation which in the opinion of the study invesgitors would make additional phlebotomy and/or marrow collection onerous and/or risky to the patient.