Serum phosphorus level is related to degree of clinical response to up-titration of heart failure pharmacotherapy.

Serum phosphorus abnormalities may pose a risk on the cardiovascular system. In heart failure (HF) phosphorus homeostatic mechanisms are altered and may be modified by modern HF therapy. The impact of therapy optimization on phosphorus abnormalities and related outcome remains unknown. In 722 patients with HF subjected to treatment up-titration we analyzed the prevalence of serum phosphorus abnormalities and their relation to HF severity on top of optimal treatment, and we assessed adjusted risk of phosphorus abnormalities at different stages of HF. We analyzed predictors of hypo- and hyperphosphatemia and relation to prognosis. Hypophosphatemia was associated with better response to therapy, was more prevalent in milder HF, and the association was independent of age, sex, BMI, etiology of HF, kidney function and the use of diuretics. Hypophosphatemic patients lost more phosphorus into urine. They had also less catabolic profile. Patients with hyperphosphatemia on top of optimal therapy responded worse to treatment. Hyperphosphatemia was more prevalent in advanced HF, but the effect was attenuated after adjustment for potential confounders. Clinical and biochemical profiles of hyperphosphatemics suggested domination of catabolism. Neither hypophosphatemia nor hyperphosphatemia modifies the outcome Serum phosphorus abnormalities are related to HF severity on top of optimal therapy. Hypophosphatemia occurring on HF up-titration therapy likely has a multifactorial pathophysiology comprising of urinary phosphorus wasting and refeeding effects. Hyperphosphatemia is linked to the catabolic profile but the effect of renal impairment can't be ruled out. The prognostic impact of serum phosphorus abnormalities remain to be established.