February 2, 2017

Kidney stones are on the rise. One cause is a condition called hyperoxaluria — when a person has too much oxalate in his or her urine. Oxalate is a natural chemical in the body, and it’s also found in certain types of food. There is no known need for oxalate by the human body, it is normally eliminated as waste through the kidneys. But too much oxalate in the urine can cause serious problems when the excess oxalate binds with calcium in the urine to form kidney stones.

The primary hyperoxalurias are autosomal recessive disorders of which three have been described at the molecular level.

  • Primary hyperoxaluriatype 1 (PH1) is caused by mutations in AGXT which result in dysfunction of the vitamin B6 (pyridoxine) dependent liver specific peroxisomal enzyme alanine: glyoxylate aminotransferase (AGT)
  • Primary hyperoxaluriatype 2 (PH2) arises from mutations in GRHPR with subsequent dysfunction of the enzyme glyoxylate/hydroxypyruvate reductase (GRHPR).
  • Primary hyperoxaluriatype 3 (PH3) arises from mutations in HOGA1 which is encodes the mitochondrial enzyme 4-hydroxy-2-oxoglutarate aldolase.

Hyperoxaluria can be caused by eating too many oxalate-rich foods, an intestinal disease or an inherited (genetic) disorder. In some persons the cause of the disease is not known, but may result from changes in the way kidneys handle normal amounts of body oxalate. Hyperoxaluria is uncommon, though can be found in about 20 percent of individuals with kidney stones. Quick diagnosis and treatment of hyperoxaluria is important to the long-term health of the kidneys.


Dietary hyperoxaluria – Eating a diet of high oxalate content foods can cause high levels of oxalate in the urine and can increase your risk of hyperoxaluria or kidney stones. Generally, if diet changes are made the urine oxalate will then decrease.

Enteric hyperoxaluria – Several intestinal diseases, including Crohn’s disease and short bowel syndrome as a result of surgical procedures like Bariatric surgery may increase the absorption of oxalate from foods, which can then increase the amount of oxalate excreted in the urine. Avoiding, foods high in oxalate in particularly important.

Primary hyperoxaluria (PH) – Is a rare, inherited (genetic) disorder of liver metabolism that often results in life-threatening damage to the kidneys. In this type, the liver doesn’t create enough of a certain protein (enzyme) that prevents overproduction of oxalate, or the enzyme doesn’t work properly. Unlike dietary or enteric hyperoxaluria, the amount of oxalate in the urine is not greatly affected by changes in dietary oxalate.


Commonly, kidney stones are the first sign of hyperoxaluria. Kidney stones are uncommon in childhood. Kidney stones that form in children and teenagers are likely to be caused by an underlying condition, such as hyperoxaluria. For this reason, all young people with kidney stones should have a thorough evaluation, including measurement of oxalate in the urine. Adults with recurrent kidney stones also should be evaluated for oxalate in the urine.

Symptoms of a kidney stone can include the following –

  • Severe or sudden abdominal or flank pain
  • Blood in the urine
  • Frequent urge to urinate
  • Pain when urinating
  • Fever and chills
  • Primary hyperoxaluria (PH) that goes untreated can eventually damage your kidneys. Over time your kidneys may stop working. For some people, this is the first sign of the disease.

Symptoms of kidney failure can include the following –

  • Decrease in urine output or no urine output at all
  • Feeling generally ill, tired or heavy fatigue
  • Loss of appetite, nausea and vomiting
  • Pale skin color related to anemia

Oxalosis in its late stages can cause a variety of complications outside the kidney, including bone disease, anemia, skin ulcers, heart and eye problems, and in children, a failure to develop and grow normally.


Medications – Prescription doses of vitamin B-6 can be effective in reducing oxalate in some people with hyperoxaluria. Oral preparation of neutral phosphates and citrate also can be effective to help prevent the formation of calcium oxalate crystals. Other medications like thiazide diuretics may also be considered, depending on the abnormalities present in the urine.

High fluid intake – If people have normal kidney function the doctor will likely tell them to drink more water or other fluids. The extra fluid flushes the kidneys, prevents oxalate crystal buildup and helps prevent kidney stones from forming. Most important — drinking enough fluid will help reduce the chances of a kidney stone.

Dietary modifications – For patients with enteric or dietary hyperoxaluriaz changes in diet may include restricting foods high in oxalate, limiting salt, decreasing sugar and reducing animal protein such as meat, eggs and fish. Also, it is important to ensure that people are getting enough calcium from food. Dietary restrictions may not be as important for people with primary hyperoxaluria. Follow the advice of the doctor or registered dietician.

Kidney stone management – Kidney stones are common in people with hyperoxaluria, but they don’t always need to be treated. If large kidney stones are causing pain or blocking urine flow, people may need to have them removed or broken up so they can pass in the urine.

Dialysis and transplant – Depending on the severity of the hyperoxaluria, people may eventually lose kidney function. Kidney dialysis may help temporarily, but it doesn’t keep up with the amount of oxalate produced.

Alternative Treatment

Magnesium intake may decrease the risk for kidney stones.

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