Differential Diagnosis for Anemia and Mild Hypercalcemia

The combination of anemia and mild hypercalcemia presents a complex clinical picture that can be associated with various conditions. Here's a structured approach to the differential diagnosis:

• Single Most Likely Diagnosis

  • Multiple Myeloma: This is a plasma cell disorder that can cause anemia due to bone marrow infiltration and hypercalcemia due to bone destruction. The presence of both anemia and hypercalcemia, especially in an older adult, should prompt consideration of multiple myeloma.

• Other Likely Diagnoses

  • Primary Hyperparathyroidism: This condition leads to hypercalcemia due to excessive parathyroid hormone production. Anemia can occur due to various reasons, including vitamin D deficiency or bone marrow suppression.
  • Vitamin D Intoxication: Excessive intake of vitamin D can lead to hypercalcemia. Anemia might not be a direct consequence but can coexist due to other nutritional deficiencies or underlying health conditions.
  • Malignancy (e.g., Breast, Lung, or Kidney Cancer): Certain cancers can cause hypercalcemia through the production of parathyroid hormone-related protein (PTHrP) or by bone metastasis. Anemia is common in cancer patients due to chronic disease, blood loss, or chemotherapy.

• Do Not Miss Diagnoses

  • Hypercalcemia of Malignancy with PTHrP: Similar to malignancy mentioned above, but emphasizing the importance of not missing a potentially life-threatening cancer diagnosis.
  • Sarcoidosis: This condition can cause hypercalcemia due to increased vitamin D conversion to its active form. Anemia can occur due to chronic inflammation or granulomatous infiltration of the bone marrow.
  • Familial Hypocalciuric Hypercalcemia (FHH): Although typically asymptomatic, FHH can present with mild hypercalcemia. Anemia might not be directly related but could coexist.

• Rare Diagnoses

  • Lymphoma: Certain types of lymphoma can cause both anemia and hypercalcemia, though this is less common compared to other malignancies.
  • Paget’s Disease of Bone: This condition can lead to hypercalcemia and, in rare cases, anemia, especially if there's significant bone marrow involvement.
  • Thyroid Disorders: Hyperthyroidism can rarely cause hypercalcemia, and anemia might coexist due to other factors. Hypothyroidism is less likely to cause hypercalcemia but can be associated with anemia.

Each of these diagnoses has a different set of implications for patient management and prognosis, highlighting the importance of a thorough diagnostic workup to determine the underlying cause of anemia and hypercalcemia.