Introduction

Gitelman syndrome is a kidney disorder causing excess loss of salt from the body via the urine. It is named after Dr Hiller Gitelman who initially identified the condition in 1966.¹ Gitelman syndrome is extremely rare and affects about 1 to 10 in 40,000 people in the UK. It affects both males and females equally and is usually diagnosed in adults.² This article will give an overview of Gitelman syndrome and elaborate on the dietary recommendations that are part of managing the syndrome.

Overview of Gitelman syndrome

Symptoms

Some people with Gitelman do not have any symptoms, while others show symptoms like:^2,3 

• Fatigue
• Muscle cramping and weakness
• Low blood pressure
• Pain in the joints
• Thirst
• Salt craving
• Numbness in the hands and feet
• Frequent urination

Causes

Gitelman syndrome is caused by a mutation in the SLC12A3 gene and is inherited in an autosomal recessive manner. ​​This gene affects the distal convoluted tubule in the kidney, which filters the blood and reabsorbs salt and potassium. If the gene is defective, salt and potassium are lost through the urine instead of being reabsorbed into the blood.¹

Diagnosis

Usually, a blood test and urine test are done to diagnose Gitelman syndrome. The blood test would show low levels of potassium, magnesium and calcium, and the urine test would indicate low levels of calcium. Genetic testing may be done if there is a family history of the syndrome.¹

Treatment¹

Gitelman syndrome affects the kidneys but does not affect the structure of the kidneys,  hence dialysis and kidney transplants are usually not needed. Therefore, the treatment for Gitelman syndrome focuses on increasing the salt intake through food or providing supplements. This usually helps manage the symptoms.

People with Gitelman syndrome are advised to follow a diet high in salt, potassium and magnesium under strict monitoring by a specialist kidney dietitian. The treatment may involve high doses of potassium and magnesium supplements which can cause side effects like abdominal pain and diarrhoea. Salt may be given intravenously when the person is ill or undergoing surgical procedures.

Non-steroidal medications may be prescribed to help the kidneys retain the potassium and magnesium. Potassium-sparing diuretics may be used to increase the amount of fluid leaving the body via the urine while retaining the potassium that would have otherwise been lost.

Gitelman syndrome requires lifelong monitoring and treatment. The amounts of supplements and medications recommended can change over time. Lack of treatment could deplete potassium and magnesium levels in the blood to such low levels that it can cause heart problems.

Dietary approach to Gitelman’s syndrome^4,5

Sodium 

To manage the loss of salts, unrestricted access to a salt diet is recommended. Foods rich in salts include smoked food like kippers, cured meat, salted nuts and crisps, tinned soup, tomato ketchup, soy sauce, parmesan cheese, pickles etc. These foods go alongside sodium chloride tablets. However, it is important to be aware that most salty foods include processed meat, chips, snacks, and salty bakery goods and the prolonged use of these is unhealthy and could lead to other degenerative diseases. 

Potassium

The regular intake of potassium-rich foods like fruits (oranges, bananas papaya, prunes, raisins, mango, melon (cantaloupe), pears, peach, strawberries, coconut, pineapples), vegetables (baked potatoes, sweet potatoes, spinach, mushrooms, kale, brussels sprouts, asparagus), lentils, yoghurt, chocolate, meat, poultry, and fish is recommended to increase dietary potassium. There are differences in how these sources affect the body. While meat can increase acid levels in the body because it contains proteins that produce sulfuric acid, fruits and vegetables on the other hand tend to produce a more alkaline effect due to their organic acids. Their carbohydrates help potassium enter cells by boosting insulin levels. It is also important to note that cooking can reduce the potassium content of these foods. Boiling food in water is a common method that causes potassium loss. However, if one drinks the cooking water, the potassium can be retained. Steaming vegetables could be a better option because it preserves potassium, which remains in the food rather than being lost in the water. Some potassium-rich foods like chocolate, potatoes, sweet potatoes, peanuts, pumpkin seeds, fruit juices, and cereals are high in carbohydrates or fats and should be eaten in moderation to avoid excessive calorie intake.

When potassium supplements are taken orally, they should be in the form of potassium chloride, as this helps replace the lost chloride. Potassium supplements can have serious side effects such as vomiting, diarrhoea, and gastric ulcers. To reduce these side effects, these supplements should be taken with food and slow-release formulations should be opted for. If oral potassium is not well-tolerated or adequate levels cannot be achieved, intravenous potassium chloride may be necessary.

Magnesium

Magnesium deficiency causes an increase in the excretion of potassium through urine. To manage low magnesium levels, dietary changes and oral supplements are necessary. Magnesium is found in both plant and animal foods, like legumes, nuts, green leafy vegetables, avocado, soybean, pumpkin seeds, nuts, bananas, whole grains, dark chocolate, oysters and fish. Processed foods, such as refined grains, have lower magnesium levels, so whole grains would be a better choice. Oral magnesium supplements can help correct magnesium deficiency and also enhance potassium absorption. However, high doses of magnesium can cause abdominal pain and diarrhoea. To minimise these issues, supplements should be taken in smaller, more frequent doses (3–4 times a day) and with meals. For Gitelman Syndrome patients with low magnesium levels, it’s also important to check vitamin D levels, as magnesium is crucial for vitamin D metabolism.

Apart from supplementation, patients with Gitelman syndrome should avoid foods that can cause a loss of potassium and magnesium. For instance, liquorice root can cause a depletion in potassium levels. Patients should also avoid excess use of alcoholic beverages as it can lead to electrolyte disorders and hence cause depletion in potassium and magnesium levels. Some beverages, such as fruit juice, bicarbonate-rich beverages, and almond-based beverages, cause a fall in potassium levels. Patients should limit fruit juice intake given their high organic acid and sugar content. As an alternative, a moderate amount of fresh fruit which has a higher content of potassium and less carbohydrates is preferable.

FAQs

What does autosomal recessive inheritance imply?¹

Autosomal recessive inheritance is when a healthy person has two normal copies of the gene i.e., one from each parent. A carrier is a person with one copy of the gene that works normally while one does not. This normal copy of the gene is sufficient to do the job and hence they are asymptomatic people. However, they could pass down the defective gene to their child. People with Gitelman syndrome have neither copies of the gene working properly, causing the kidneys to excrete salt via the urine. When both parents are carriers, the child could be healthy with two normal genes or a healthy asymptomatic carrier like the parents, with one healthy and one faulty gene or affected with Gitelman syndrome given that both the genes are faulty. This is called autosomal recessive inheritance.

Summary

Gitelman syndrome is a rare genetic disorder characterised by an excess loss of salts like potassium and magnesium, through urine. This condition affects around 1 to 10 people per 40,000 in the UK. It is caused by mutations in the SLC12A3 gene, which affects the kidney's ability to reabsorb salt and potassium.

The symptoms of Gitelman syndrome are fatigue, muscle cramping, low blood pressure, joint pain, increased thirst, salt cravings, and frequent urination. Diagnosing the syndrome includes blood and urine tests that can reveal low levels of potassium, magnesium, and calcium, along with genetic testing if there is a family history.

Treatment mainly focuses on dietary management and supplementation to compensate for the loss of salts and hence manage symptoms. A high-salt diet, complemented by sodium chloride tablets, is recommended. Patients are recommended potassium-rich foods, including fruits, vegetables, meat, and fish. However, cooking methods like boiling can reduce the potassium content of food, and steaming should be preferred. Moderation is important for potassium-rich foods high in carbohydrates and fats to avoid an excess calorie intake. Oral potassium supplements, preferably in the form of potassium chloride, are used to correct deficiencies, though they can cause side effects such as nausea, diarrhoea, and gastric ulcers. To reduce these effects, supplements should be taken with food and in slow-release formulations. If oral supplements are insufficient, intravenous potassium chloride may be required. Magnesium supplementation is also crucial since magnesium deficiency can lead to increased potassium excretion. Sources of magnesium in the diet could include nuts, legumes, green leafy vegetables, and whole grains. Processed foods should be avoided due to their lower magnesium content. Magnesium supplements should be taken in small frequent doses with meals to reduce gastrointestinal side effects. Vitamin D levels should be monitored as magnesium is essential for its metabolism.

Patients should avoid substances that can increase potassium and magnesium loss, such as liquorice root and excessive alcohol consumption. Beverages high in sugar and organic acids, like fruit juices, should be consumed in moderation. Effective management of Gitelman syndrome requires lifelong monitoring and adjustments in treatment to maintain electrolyte balance and prevent complications.