Serum phosphate and anxiety in major depression.

Serum inorganic phosphate was measured in 33 hospitalized patients with unipolar depression. As predicted, serum phosphate showed significant negative correlations with Minnesota Multiphasic Personality Inventory scales sensitive to anxiety (Psychasthenia: -0.33) and somatic concern (Hypochondriasis: -0.51). This is consistent with previous observations of relative hypophosphatemia in patients with panic disorder. Clinical consequences of relative hypophosphatemia and the possible roles of hyperventilation or elevated peripheral catecholamines as mediators of this effect are discussed.