Gitelman Syndrome
Definition
Gitelman syndrome (GS), which is also known as familial hypokalemia-hypomagnesemia, is a rare inherited disorder in the renal tubule of the kidneys. The kidney should have reabsorbed chloride, magnesium, potassium, and sodium into the blood stream but in GS, it causes the kidney to waste these minerals instead. The urine calcium levels are usually lower than normal, in spite of the normal serum values.
This disorder does not lead to kidney failure or affect the kidney and cause it to function abnormally. Both kidneys will appear normally. The reabsorption of significant minerals and electrolytes are the problem. The fault is in the Thiazide Co-Transporter where the magnesium, sodium, and potassium are drawn into the body.
Due to the problem, these minerals are wasted in the urine, rather than being absorbed in the body. Gitelman syndrome is estimated to have occurred in 1 out of 40,000 individuals. It could fairly affect both men and women of all ethnic backgrounds.
Symptoms of Gitelman Syndrome
In most cases of adults, Gitelman’s syndrome is diagnosed to those who present no symptoms, but has unexplained hypokalemia or low levels of potassium in the blood. Often, patients will visit their physician for some other reasons and when routine laboratory work is finished, it is found that the patient has low potassium levels.
Other cases occurs when a patient is having symptoms, but does not know what exactly is wrong. Majority of the symptoms that these individuals experience are from low potassium and magnesium levels. Signs and symptoms of Gitelman syndrome usually present in adolescence or late childhood.
These symptoms may include:
- Cramping of muscles
- Muscle spasms that are painful
- Salt craving
- Dizziness
- Tingling sensation in the skin especially on the face
- Low blood pressure
- Fatigue
- Increased urination and thirst
- Salt cravings
- Joint pains
The symptoms of this condition widely vary in each affected individual even to those of the same family. A lot of people with GS have mild symptoms, but some have been reported to have slow growth, severe cramping of muscles, and paralysis.
Causes
Gitelman syndrome is inherited by a person in an autosomal recessive pattern, though sometimes it could happen to anyone who has no family history of the condition. GS is commonly caused by certain mutations in the SLC12A3 gene or in some instances, the disorder is a result from mutations in the CLCNKB gene.
Proteins that are produced from these genes are associated in the reabsorption of salt in the kidneys coming from the urine back into the bloodstream. Any mutations that occur in either of the genes impede the kidney’s capacity to reabsorb salt, resulting to salt wasting.
Irregularities of salt transport could also affect reabsorption of some ions; such as ions of calcium, potassium, and magnesium. The major features of the syndrome are dependent on the imbalance of ions in the body.
Diagnosis
Once the causes of the electrolyte abnormalities are determined, Gitelman syndrome is typically diagnosed through symptoms, blood or urine tests, and a physical examination. The levels of magnesium and potassium in the blood and the levels of calcium in the urine are evaluated.
Bartter syndrome which is also an inherited kidney disorder, is similar to GS so additional tests might be required to ascertain which disorder is present.
Treatment
Gitelman syndrome treatments focus on keeping the blood potassium, sodium, chloride, and magnesium at normal levels. The patient must have a diet rich in sodium and potassium by taking magnesium supplements in order to achieve the desired level of minerals. Some medications are also helpful in limiting electrolyte losses.
Patients should consult with their own physicians to get the required and prescribed medications. All individuals with Gitelman syndrome are also persuaded to sustain a high potassium and high-sodium diet.
Prognosis
In general, the long-term outcome of Gitelman syndrome is excellent although the severity of fatigue can really affect some individuals in their day to day activities. Renal insufficiency or the poor functioning of the kidneys is extremely rare in GS based on the cases reported.
References:
- http://ghr.nlm.nih.gov/condition/gitelman-syndrome
- http://rarediseases.about.com/od/kidneyurinarydisorders/a/gitelman.htm
- http://barttersite.org/what-is-gitelmans-syndrome/#more-175
- Riveira-Munoz E, Chang Q, Godefroid N, Hoenderop JG, Bindels RJ, Dahan K, Devuyst O (2007). Belgian network for study of gitelman syndrome. Transcriptional and functional analyses of SLC12A3 mutations: new clues for the pathogenesis of Gitelman syndrome. J Am Soc Nephrol, 1:1271-1283.
- Scognamiglio R, Negut C, Calò LA (2007). Aborted sudden cardiac death in two patients with Bartter’s/Gitelman’s syndromes. Clin Nephrol, 67:193-197.
- Lin SH, Cheng NL, Hsu YJ, Halperin ML (2004). Intrafamiliar phenotype variability in patients with Gitelman syndrome having the same mutations in their thiazide-sensitive sodium/chloride cotransporter. Am J Kidney Dis, 43:304-312.
