Phosphates, Phosphorus : Safety

by MedlinePlus

(Page 3 of 3)

Allergies

Avoid if allergic to any ingredients in phosphorus/phosphate preparations.

Brief Safety Summary

General: Sodium, potassium, aluminum, and calcium phosphates are likely safe when used orally in recommended doses for short-term periods by people without hyperphosphatemia, impaired kidney function, or other health conditions known to increase the risk of hyperphosphatemia (see below). Sodium phosphate is likely safe when used rectally for short-term periods in otherwise healthy individuals with normal kidney function. Long-term use or high doses used orally or rectally require monitoring of serum electrolytes. Intravenous phosphate is likely safe when used as an FDA-approved prescription drug under medical supervision in people without hyperphosphatemia, impaired kidney function, or other health conditions known to increase the risk of hyperphosphatemia (see below). Phosphate (expressed as phosphorus) intake taken via any route that exceeds the tolerable upper intake level (UL) is possibly unsafe, and may cause hyperphosphatemia (low phosphate levels), hypocalcemia (low calcium blood levels), calcification of nonskeletal tissues, and other electrolyte disturbances. Baseline electrolyte levels should be measured prior to starting phosphate therapy, including sodium, potassium, chloride, bicarbonate, calcium, phosphate, blood urea nitrogen (BUN), and creatinine. Sodium phosphate and potassium phosphate are cathartic agents, which can cause diarrhea.

Precautions/contraindications: Phosphorus/phosphate salts should be used cautiously or avoided in patients with kidney impairment, liver cirrhosis, heart failure, unstable angina, recent heart surgery, hyperphosphatemia (low phosphate), hypocalcemia (low calcium), hypokalemia (low potassium), hypernatremia (high sodium), Addison's disease, ascites, intestinal obstruction or ileus, bowel perforation, severe chronic constipation, acute colitis, toxic megacolon, hypomotility syndrome (such as hypothyroidism, scleroderma), or gastric retention. Sodium phosphate enemas should be avoided in people with congenital or acquired abnormalities of the intestine. There is a particularly increased risk of hyperphosphatemia and hypocalcemia in people with kidney disease, liver disease, hypoparathyroidism, severe hyperthyroidism, Addison's disease/adrenal insufficiency, severe heart disease, lactic or respiratory acidosis, rhabdomyolysis, or tumor lysis syndrome. Hyperphosphatemia from dietary causes may occur when kidney function is only 20% of normal, and even typical levels of dietary phosphorus may lead to hyperphosphatemia. Serum electrolytes should be closely monitored when phosphates are used by people with any degree of kidney impairment.

Toxicity/toxicity management: Excessive intake of phosphates can cause potentially serious or life-threatening toxicity. Intravenous, oral, or rectal/enema phosphates may cause electrolyte disturbances including hypocalcemia (low calcium blood levels), hypomagnesemia (low magnesium blood levels), hyperphosphatemia (high phosphorus blood levels), or hypokalemia (low potassium levels). Calcification of non-skeletal tissues (particularly in the kidneys), severe hypotension (low blood pressure), dehydration, metabolic acidosis, acute kidney failure, or tetany can occur. Death has been reported in infants or adults with oral, rectal, or intravenous phosphates, particularly in those at increased risk for electrolyte disturbances, and in those receiving more than 45 or 90 milliliters in a 24-hour period. Late symptoms may include abdominal pain, vomiting of phosphorescent materials, bloody vomiting and diarrhea, headache, limb aches, tongue coating, foul breath, weakness, yellow conjunctivae (whites of the eyes). Rare complications may include confusion, convulsions (seizures), headache, dizziness, numbness, tingling, pain, weakness, anxiety, increased thirst, muscle cramps, or fatigue. Abnormal heart rhythms, shortness of breath, foot/leg swelling, and weight gain have been reported.Management of toxicitymay include sulfate of copper emetic, or lavage with Epsom salts in water (repeated every hour); repeated small doses of sulfate of copper and large doses of bicarbonate of soda. Oxygen inhalation, external heat, camphor, old oil of turpentine, and permanganate of potassium have been recommended.

Neurologic: Rare complications may include confusion, convulsions (seizures), headache, dizziness, numbness, tingling, pain, weakness, anxiety, increased thirst, muscle cramps, or fatigue.

Gastrointestinal: Sodium phosphate and potassium phosphate are cathartic agents, and may cause diarrhea. To minimize this side effect, phosphates may be administered in divided doses 3 or 4 times daily. Nausea, vomiting, or gastrointestinal irritation can occur. A reduction in dosage may be necessary to minimize diarrhea. Potassium acid phosphate may cause dyspepsia in patients with a history of peptic ulcer disease. Aluminum phosphate can cause constipation.

Renal (kidney): Excessive phosphate intake can be complicated by kidney damage or calcification. Impaired kidney function increases the risk of hyperphosphatemia, which can occur from dietary intake when kidney function is only 20% of normal, and even typical levels of dietary phosphorus may lead to hyperphosphatemia. Serum electrolytes should be closely monitored when phosphates are used by people with any degree of kidney impairment. Decreased urine output may occur. Oral ingestion of large amounts of sodium dihydrogen phosphate can lower urine pH.

Conditions which may be worsened with excessive phosphorus/phosphate supplementation: Burns, heart disease, pancreatitis, rickets, osteomalacia (softening of bones), underactive parathyroid glands (with sodium phosphate or potassium phosphate), dehydration, underactive adrenal glands (potassium phosphate may increase the risk of hyperkalemia), edema, high blood pressure, liver disease, toxemia of pregnancy, hyperphosphatemia, kidney disease.

Pregnancy and Breastfeeding

Tolerable Upper Intake Level (UL) for Phosphorus: The recommended UL in pregnant women is 3.5 grams/day, and in breastfeeding women is 4 grams/day.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

Antacids: Antacids containing aluminum, calcium, or magnesium can bind phosphate in the gut and prevent its absorption, potentially leading to hypophosphatemia (low phosphate levels) when used chronically.

Anticonvulsants: Some anticonvulsants (including phenobarbital and carbamazepine) may lower phosphorus levels and increase levels of alkaline phosphatase.

Cholestyramine (Questran), Colestipol (Colestid): Bile acid sequestrants can decrease oral absorption of phosphate. Therefore, oral phosphate supplements should be administered at least one hour before or four hours after these agents.

Corticosteroids: Steroids may increase urinary phosphorus levels.

Diuretics: Potassium supplements or potassium-sparing diuretics taken together with a phosphate may result in high blood levels of potassium (hyperkalemia).

Medications affecting electrolyte levels: Medications that may affect electrolyte levels should be used cautiously with phosphates. Examples include: amiloride (Midamor); angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Lotensin), captopril (Capoten), enalapril (Vasotec), fosinopril (Monopril), lisinopril (Zestril, Prinivil), quinapril (Accupril), or ramipril (Altace); cyclosporine; cardiac glycosides (Digoxin); heparins; anti-inflammatory drugs; potassium-containing agents; salt substitutes; spironolactone (Aldactone); and triamterene (Dyrenium).

Interactions with Herbs and Dietary Supplements

Calcium: May impair phosphates in the body, and result in calcium deposits in tissues.

Pumpkin seed: May increase urine phosphates.

Vitamin D: Excessive doses of calcitriol, the active form of vitamin D (or its analogs) may result in hyperphosphatemia (high phosphate levels).

Interactions with Foods

Cola drinks: Contain significant amounts of phosphate, and excessive intake can result in hyperphosphatemia and hypocalcemia.

Ethanol: May increase urinary phosphorus. Wine may enhance absorption of phosphorus (as well as calcium and magnesium).

High fructose diets: May increase urinary loss of phosphorus.

Interactions with Laboratory Tests

Acid phosphatase: Phosphates can cause a false-decrease in some acid phosphatase serum test results.

Alkaline phosphatase: Phosphates can cause a false-decrease in some alkaline phosphatase serum test results.

Ammonia: Phosphates can cause a false-decrease in some plasma ammonia test results by inhibiting formation of indophenol color in Berthelot reaction.

Calcium: Phosphates can increase fecal levels in some assays. Phosphates can cause a false-decrease in some serum and urine test results by inhibiting emission in some flame methods and by competing with EDTA for calcium.

Magnesium (urine levels): Phosphates can decrease urine levels.

Parathyroid Hormone: Phosphates can increase plasma levels.

Potassium: Phosphates (except potassium phosphate) may decrease serum levels.

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