From the Guidelines
Hypophosphatemia symptoms commonly include fatigue, proximal muscle weakness, and bone pain, which can mimic iron deficiency anemia (IDA) symptoms, and can also lead to more severe complications such as asthenia, myopathy, and respiratory failure. These symptoms are typically observed with moderate hypophosphatemia, defined as a phosphate level less than 2.5 mg/dL but greater than 2 mg/dL 1. The severity and duration of hypophosphatemia can vary, with some cases being severe and prolonged, lasting up to 6 months after administration of certain intravenous iron formulations 1.
Symptoms of Hypophosphatemia
- Fatigue
- Proximal muscle weakness
- Bone pain
- Asthenia
- Myopathy
- Respiratory failure
The symptoms of hypophosphatemia occur because phosphate is essential for various bodily functions, including metabolism, bone mineralization, cellular structure, and enzymatic function 1. The physicochemical properties of certain intravenous iron formulations, such as ferric carboxymaltose (FCM), can trigger a sharp increase in the phosphoturic hormone, iFGF23, leading to hyperphosphaturic hypophosphatemia 1.
Severity of Hypophosphatemia
- Mild: phosphate level less than the lower limit of normal (LLN) but greater than 2.5 mg/dL
- Moderate: phosphate level less than 2.5 mg/dL but greater than 2 mg/dL
- Severe: phosphate level less than 2 mg/dL but greater than 1 mg/dL
- Potentially life-threatening: phosphate level less than 1 mg/dL
It is essential to recognize and manage hypophosphatemia promptly to prevent severe complications and improve patient outcomes 1.
From the Research
Symptoms of Hypophosphatemia
The symptoms of hypophosphatemia can be nonspecific and most patients are asymptomatic 2. However, severe hypophosphatemia may cause:
- Skeletal muscle weakness
- Myocardial dysfunction
- Rhabdomyolysis
- Altered mental status 2
- Reversible depression of myocardial function
- Acute respiratory failure
- Coma
- Osteomalacia
- Renal tubular acidosis
- Hemolysis 3
- Peripheral neuropathy with paresthesias and metabolic encephalopathy, resulting in confusion and seizures 4
- Severe ataxia and tetra paresis 4
Severity of Hypophosphatemia
Hypophosphatemia can be classified as mild, moderate, or severe, depending on the serum phosphate level:
- Mild: phosphorus level, 2-2.5 mg/dL
- Moderate: 1-1.9 mg/dL
- Severe: <1 mg/dL 5
Clinical Disorders Associated with Hypophosphatemia
Hypophosphatemia can be associated with various clinical disorders, including: