Bartter syndrome
Bartter syndrome refers to a group of kidney diseases, all of which manifest with low potassium levels (hypokalemia) and metabolic alkalosis. [1] This syndrome is a genetic disease inherited asautosomal recessive trait. [2]
Epidemiology
Most cases are discovered during the first year of life or early adolescence. Bartter syndrome can also be diagnosed prenatally. Those diagnosed early typically manifest with more serious electrolyte disorders and symptoms. The syndrome has no gender, racial or ethnic predilection. [3]
Causes
Five gene defects are linked to Bartter syndrome. An affected person has kidneys which are unable to reabsorb sodium hence lose sodium too much. This in turn elevates Aldosterone level of the body which will then cause the kidney to remove too much potassium. Hypokalaemia results.
Normal acid balance is also disrupted which causes metabolic alkalosis. The upshot is too much calcium in the urine. [4]
Signs and Symptoms
A person with Bartter syndrome may manifest with the following: [5] [3]:
· constipation
· short stature
· increased frequency of urination
· signs of volume depletion such as low blood pressure
· kidney stone
· muscle spasms and weakness
· triangular face
· large eyes
· protruding ears
· sensorineural hearing loss
· rickets
Diagnosis
Urine is obtained to determine electrolyte levels (potassium, aldosterone and chloride). Urine collection must be properly timed to yield accurate results. [3] Other tests might be done to determine blood chloride and hormone levels like renin and aldosterone. Kidney biopsy may also be performed to reveal excess growth of kidney cells termed juxtaglomerular apparatus. [4]
Ultrasonography is used to diagnose antenatal Bartter syndrome which would show polyhydramnios (excess amniotic fluid) and intrauterine growth retardation. Level of amniotic chloridemay also be increased. [3]
Gene analysis is done to study sites of mutations. [3]
Treatment
Blood potassium level is kept above 3.5 mEq/L which is often done by taking potassium supplements or taking diets rich in potassium. Salt and magnesium supplements are frequently prescribed. Nonsteroidal anti-inflammatory drugs (NSAIDs), usually on high doses, may also be used. [4]
If there is tetany or muscle spasm, calcium supplements are given. Short stature is treated withgrowth hormone. [3]
References:
1. http://qjmed.oxfordjournals.org/content/93/4/207.full
2. http://barttersite.org/bartters-syndrome/
3. http://emedicine.medscape.com/article/238670-overview#a0199
4. http://www.nlm.nih.gov/medlineplus/ency/article/000308.htm
5. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001352/
