Differential Diagnosis for Bone Pain, Depression, Loss of Memory, and Fatigability

• Single Most Likely Diagnosis

  • Hyperparathyroidism (specifically, Primary Hyperparathyroidism): This condition is characterized by elevated serum calcium levels and normal or elevated parathyroid hormone (PTH) levels. The symptoms of hyperparathyroidism can include bone pain (due to increased bone resorption), depression, cognitive impairments such as loss of memory, and fatigability. The elevated calcium levels can affect neuromuscular function and bone health, leading to these symptoms.

• Other Likely Diagnoses

  • Vitamin D Deficiency: This can lead to secondary hyperparathyroidism, causing increased bone resorption and potentially similar symptoms, including bone pain and fatigue. However, the primary issue here would be low vitamin D levels rather than directly high serum calcium.
  • Chronic Kidney Disease (CKD): CKD can lead to disturbances in calcium and phosphate metabolism, including secondary hyperparathyroidism. This can cause bone pain, fatigue, and potentially cognitive symptoms due to the buildup of toxins.

• Do Not Miss Diagnoses

  • Hypercalcemia of Malignancy: Although less common, hypercalcemia can be a complication of various cancers (e.g., multiple myeloma, lung cancer). The symptoms can include bone pain, fatigue, depression, and cognitive impairments. Missing this diagnosis could be fatal due to the underlying malignancy.
  • Vitamin B12 Deficiency: This can cause fatigue, depression, and cognitive impairments, including loss of memory. While it doesn't directly cause bone pain, it's a condition that significantly impacts quality of life and can have severe neurological consequences if left untreated.

• Rare Diagnoses

  • Osteomalacia: A condition characterized by softening of the bones due to defective bone mineralization, often due to vitamin D deficiency or phosphate deficiency. It can cause bone pain and muscle weakness but is less commonly associated with the full spectrum of symptoms described.
  • Paget's Disease of Bone: A chronic condition that can result in enlarged and misshapen bones due to abnormal bone destruction and regrowth. While it can cause bone pain, its association with depression, loss of memory, and fatigability is less direct and would be considered a rare cause of this specific constellation of symptoms.