Hypophosphatemia in Critical Care Complications

     
       

 

         
       

Hypophosphatemia causes muscle weakness, particularly respiratory muscles.

The problem with being presented with a low serum phosphate result, is that it tells you little about the overall state of intracellular phosphate, and therefore whether total body phosphate depletion exists.

In general, muscles do not function well in hypophosphatemic states. This relates to the importance of phosphate as the body’s source of chemical energy. Hypophosphatemic causes weakness of respiratory muscles, particularly the diaphragm, and causes a leftward shift of the oxyhemoglobin dissociation curve (increasing the tendency for hemoglobin to cling onto oxygen). Patients who are hypophosphatemic may be slow to wean from mechanical ventilation (Agusti, AG; Hypophosphatemia; CCM 1984) (Aubier, M; Hypophosphatemia; NEJM 1985). As one would expect, hypophosphatemia causes skeletal muscle weakness, which may mimic a myopathy. In addition, low serum phosphate my interfere with blood cell function and cause increased red cell fragility.

Hypophosphatemia may cause myocardial dysfunction (Zazzo JF ICM 1995; hypophosphatemia), and may make the myocytes less sensitive to the stimulatory effects of catecholamines. This effect is reversible. Other complications of hypophosphatemia are listed in the table below.

Clinical Manifestations of Hypophosphatemia

Musculoskeletal

Cardiovascular

Pulmonary

Neurologic

Hematologic  Metabolic

Chronic Myopathy

Cardiomyopathy

Respiratory Failure

Delirium

Impaired oxygen release

Rhabdomyolysis

Arrhythmias (ventricular)

Failure to wean

Seizures

Hemolysis

 

Osteopenia

 

 

Encephalopathy

Leucocyte dysfunction

Osteomalacia

 

 

Hallucinations

Metabolic Acidosis

 

 

 

Peripheral Neuropathy

Glucose Intolerance

         
                   
       

         
     

       
       

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