A 52-year-old man arrives by ambulance complaining of several weeks of progressive lethargy. He is stuporous but arousable and complains of back pain and constipation. His vital signs are normal. Physical examination is remarkable for sausage-shaped retinal vessels and decreased consciousness. Neurologic examination reveals no focal findings. A chest x-ray shows a left pleural-based density with associated bony destruction. An abdominal series is remarkable for osteopenia of the pelvis. The hematology laboratory reports the machines keep clogging up. The hematocrit is 21%; RBCs are hypochromic and microcytic with marked rouleaux formation; WBC is 14,000/mm3 with no left shift. Choose the correct statement:
The patient will probably have hypernatremia.
The diagnostic test of choice is a CT or MRI scan of the head.
Treatment includes fluid restriction.
Hypocalcemia may be present.
The radiographic findings are virtually diagnostic, but the diagnostic tests of choice include a serum viscosity determination.
The hyperviscosity syndrome occurs when either abnormal amounts of serum protein are produced (multiple myeloma or Waldenström macroglobulinemia) or from the presence of massive numbers of white blood cells (chronic myelocytic leukemia [CML] and blast crisis). Vascular stasis and capillary sludging result in headache, fatigue, lethargy, seizures, and coma. Laboratory abnormalities in the paraproteinemias include RBC rouleaux formation, factitious hyponatremia, and abnormally high serum viscosity. Protein electrophoresis is diagnostic. Treatment of the hyperviscosity syndromes include hydration and plasmapheresis. Blast crisis and hyperviscosity in CML are treated with hydration and chemotherapy. Multiple myeloma is a common cause of destructive rib lesions and generalized osteopenia in patients older than 40 years. Additional clinical features include back pain (from lumbar vertebral fractures), constipation, and a decreased mental status (from hypercalcemia).