Information is included from: Merck Manual, Mayo Clinic, Healthline.com, Cleveland Clinic, and American Heart Association, GB Healthwise.
A patient recently asked me about her high blood sodium level on her most recent labwork. I recommended she ask her MD about the reading, but wanted to provide some information on blood sodium levels.
Her next question was: “Is this high blood sodium responsible for my hypertension?” I also wanted to provide some current information on sodium/salt and hypertension.
The following is information I researched for my patient. I decided to share it as so many people are confused about sodium in their blood, sodium intake from food/drinks, and does sodium impact blood pressure?
Let’s start with sodium listed on your lab work.
Sodium is both an electrolyte and mineral. It is important for nerve and muscle function. The kidneys keep blood sodium in balance through a variety of mechanisms.
Sodium gets into your blood from food and drink. Excessive blood serum exits the blood through urine, stool, and sweat.
Low Blood Sodium is called HYPONATREMIA and is more often a problem in older adults.
Hyponatremia can cause damage to cells as it makes the cells swell with too much water. This may be particularly dangerous in areas such as the brain.
Hyponatremia is more common in older adults because they’re more likely to take medications or have medical conditions that put them at risk of the disorder.
Hyponatremia treatments may include changing a medication that affects your sodium level, treating the underlying disease, changing the amount of water you drink or changing the amount of salt in your diet.
Hyponatremia can be caused by:
• certain pain medications
• large burns on the skin
• kidney disease
• liver disease or cirrhosis
• severe diarrhea or vomiting
• heart failure
• high levels of certain hormones, such as antidiuretic hormone or vasopressin
• drinking too much water
• not urinating enough
• excessive sweating
• ketones in the blood, known as ketonuria
• underactive thyroid, or hypothyroidism
• Addison’s disease, which is low hormone production in the adrenal gland
High Blood Sodium is called HYPERNATREMIA
In hypernatremia (hi-per-na-tree-mia), the level of sodium in blood is too high. High blood sodium is defined as a sodium level that exceeds 145 mEq/L.
Symptoms of hypernatremia include:
• swelling in hands and feet
• rapid heartbeat
Hypernatremia is most often a problem in older adults, infants, and people who are bedridden.
Causes of hypernatremia include:
• not drinking enough water
• drinking salty water
• eating too much salt
• excessive sweating
• low levels of hormones such as vasopressin
• high levels of aldosterone
• Cushing’s syndrome, caused by excessive cortisol
Certain medications can also potentially cause hypernatremia. These include:
• birth control pills
• nonsteroidal anti-inflammatory pain medications
Usually, fluids are given intravenously to slowly reduce the sodium level in the blood.
SALT and HYPERTENSION
You may have been told by your healthcare provider to reduce the salt in your diet to treat hypertension.
Table salt is composed of sodium and chloride. One teaspoon of salt contains about 2,400 mg of sodium. The body requires a balance of sodium and water to function properly. Too much salt or too much water in your system will upset the balance. When you’re healthy, your kidneys get rid of extra sodium to keep the correct balance.
How much sodium do I need?
Most people eat too much sodium, often without knowing it.
The average American eats about 3,400 mg of sodium a day!
The American Heart Association recommends no more than 2,300 milligrams (mgs) a day and an “ideal limit” of no more than 1,500 mg per day for most adults.
1 tsp of salt contains 2400mg sodium.
What foods should I limit?
The best way to reduce sodium is to limit prepackaged, processed and prepared foods, which tend to be high in sodium including:
• Breads and rolls
• Cold cuts and cured meats
• Fast Food
• Tomato products and sauce
• Cheeses and buttermilk
• Salted snacks, nuts and seeds
• Frozen dinners and snack foods
• Condiments (ketchup, mustard, mayonnaise)
• Pickles and olives
• Seasoned salts, such as onion, garlic and celery salts
• Sauces, such as barbeque, soy, steak, and Worcestershire
How can I cook with less salt and more flavor?
Avoid adding table salt to foods. Use herbs and spices to add flavor to foods. Eat fresh fruits, vegetables, lean meats, skinless poultry, fish• Choose unsalted nuts and reduced sodium canned foods.
Comparison of Sodium in Foods
Meats, poultry, fish, and shellfish
Food: Milligrams (mg.) sodium
Fresh meat, 3 oz. cooked: Less than 90 mg
Shellfish, 3 oz: 100 to 325 mg
Tuna, canned, 3 oz: 300 mg
Lean ham, 3 oz.: 1,025 mg
Food: Milligrams sodium
*Whole milk, 1 cup: 120 mg
Skim or 1% milk, 1 cup: 125 mg
*Buttermilk (salt added), 1 cup: 260 mg
*Swiss cheese, 1 oz: 75 mg
*Cheddar cheese, 1 oz : 175 mg
Low-fat cheese, 1 oz.: 150 mg
*Cottage cheese (regular), 1/2 cup: 455 mg
Food: Milligrams sodium
Fresh or frozen vegetables, and no-salt-added canned (cooked without salt), 1/2 cup: Less than 70 mg
Vegetables canned or frozen (without sauce), 1/2 cup: 55-470 mg
Tomato juice, canned, 3/4 cup: 660 mg
Breads, cereals, rice and pasta
Food: Milligrams sodium
Bread, 1 slice: 110-175 mg
English muffin (half): 130 mg
Ready-to-eat, shredded wheat, 3/4 cup: Less than 5 mg
Cooked cereal (unsalted), 1/2 cup: Less than 5 mg
Instant cooked cereal, 1 packet: 180 mg
Canned soups, 1 cup: 600-1,300 mg
Canned and frozen main dishes, 8 oz: 500-1,570 mg
Salt sensitivity is a measure of how your blood pressure responds to salt intake. People are either salt-sensitive or salt-resistant. Those who are sensitive to salt are more likely to have high blood pressure than those who are resistant to salt
When it comes to dietary sodium (salt), people naturally think about its effect on blood pressure. They think, “Too much salt in my diet will increase my blood pressure.” But not everyone who has a lot of salt develops hypertension. Part of the reason for this is that hypertension can be caused by factors other than sodium; the other part is that the effect of sodium on blood pressure is different for each individual due to their salt sensitivity.
There are many ways to measure if a person is salt-sensitive or salt-resistant. One of the methods involves eating a low-sodium diet (about 230 mg sodium or 600 mg of table salt per day) for four days, followed by four days of a high-sodium diet (about 4.6 g sodium or 12 g of table salt per day). If blood pressure increases by at least 5% at the end of the high-sodium period, the person is said to be salt-sensitive. Otherwise, he or she is salt-resistant or salt-insensitive.
Very easy testing method: Check the fit of a ring on your ring finger at each blood pressure test time. Have a low sodium breakfast, lunch, snacks. Plan a higher sodium dinner. Test blood pressure and tightness of a ring on your finger at wake up, 15 minutes after breakfast, lunch, and dinner. See if you have an over 5% increase in blood pressure and swelling of your ring finger after the high sodium meal.
Very basic “test” for sodium/salt sensitivity:
Eggs (no salt) but you may add veggies like chopped fresh tomato, onions, green peppers
Plain rice cake with “no sugar added” jelly and natural PB (no sugar added).
Burger or grilled chicken with no bun, cheese, or ketchup (not from fast food chain)
In place of a baked bun use lettuce leaves to “wrap” the burger
Handful of Unsalted Nuts
1 slice pizza
Tossed garden salad with bottled dressing
*Drink lots of water/decaf fluid throughout the day, aiming for 64 ounces or more over the entire day.
Why does salt sensitivity matter?
Salt-sensitive individuals are at higher risk for high blood pressure, cardiovascular disease, and lower survival rate later in life if they continuously live an unhealthy lifestyle or have a high-sodium diet.
Why are people salt-sensitive?
Sodium homeostasis in the human body is regulated mainly by the renin-angiotensin-aldosterone system. This system operates mainly in the kidney and in vascular smooth muscle cells. Variations in this system, due to genetic background, age, race, gender and medical history, cause the kidney of salt-sensitive individuals to handle excess sodium less efficiently. Asian or African ancestry, older age, female gender, high blood pressure, and kidney disease are all associated with salt-sensitivity.
LATEST FROM AMERICAN HEART ASSOCIATION REGARDING SALT SENSITIVITY! Salt sensitivity of blood pressure: a scientific statement from the American Heart Association [published online ahead of print July 21, 2016]. Hypertension. doi: 10.1161/HYP.0000000000000047
Hypertension affects 32.6% of the U.S. adult population and is a major risk factor for cardiovascular events and death.However, the mechanisms by which hypertension develops and is sustained are not well understood.
A major proposed mechanism for the initiation of hypertension in both humans and experimental animal models involves a fundamental defect in the capacity of the kidneys to excrete sodium.2 Over time, a compensatory increase in blood pressure (BP) and, consequently, an increase in renal perfusion pressure increase sodium excretion but also induce hypertension.
The kidneys maintain the composition of body fluids and regulate extracellular fluid volume homeostasis, and abnormalities in sodium balance play a critical role in the pathophysiology of hypertension.
Salt sensitivity of blood pressure is a quantitative trait in which an increase in dietary sodium intake engenders an increase in blood pressure.
Salt sensitivity occurs in normotensive as well as hypertensive humans and predicts increased cardiovascular events and mortality, irrespective of unchallenged BP levels.
Overall, salt sensitivity has been estimated to be present in approximately 51% of hypertensive and 26% of the normotensive population, posing a major public health problem.8 Salt sensitivity is especially common in African Americans, older adults, and in people with a higher level of BP or comorbidities such as chronic kidney disease, diabetes mellitus, or the metabolic syndrome.9 Altogether, these groups constitute more than half of the adult population in the United States.
The American Heart Association has published an up-to-date, balanced, authoritative, and comprehensive Scientific Statement that promises to increase interest in this important topic.
The article further discusses the measurement of salt sensitivity, potential demographic and environmental factors, prognostic significance, and potential surrogate markers that would eliminate the need to perform time consuming, expensive and logistically difficult analyses of human blood pressure responses to sodium loading and depletion. For clinicians, this Scientific Statement assesses implications of salt sensitivity in the management of individual patients as well as for public health at large.
The Statement concludes with a useful evaluation of knowledge gaps and methodological recommendations for measurement of salt sensitivity of BP in human studies in the future.
At present, there is no information on the treatment of salt sensitivity per se or the treatment of hypertension in patients with as opposed to without the salt sensitivity trait. If hypertension in salt sensitive individuals can be treated specifically in the future, then documenting the existence of salt sensitivity undoubtedly will become an important component of managing antihypertensive drug therapy.
IN MY OPINION:
In my opinion, the development of hypertension is not only an excess salt issue. It seems that recent research considers elevated blood pressure to be a multi-faceted health condition. It appears that genes, environment, age, people who already have hypertension, as well as comorbidities such as chronic kidney disease, diabetes mellitus, or the metabolic syndrome also impact blood pressure. These facets impact more than 50% of the adult population.
Until salt sensitivity is properly researched and proven, I find it sensible for everyone to reduce sodium intake. We are a society that enjoys processed foods, fast foods, breads, baked products, cheese, and more.
Unless your MD restricts your mg of sodium for a medical condition; kidney disease, cardiovascular disease, etc., I feel that everyone should become informed of high sodium food sources, and using common sense and knowledge, take steps to decrease intake of high sodium sources. Diane Kress.