Journal of Vita Columbia Volume 2 Issue 1 – Clinical Nutrition

Sodium: The Role of this Vital Electrolyte and Mineral in the Body

January 18th, 2022
How to cite this article:

Baila BM, Latcu CM, Grewal VP. Sodium: The Role of this Vital Electrolyte and Mineral in the Body. 2022. Journal of Vita Columbia. 2(1).


Sodium is an essential nutrient involved in maintaining normal cellular homeostasis. Moreover, it plays an important role in controlling fluid and electrolyte balance, as well as  blood pressure. Sodium disorders, hyponatremia and hypernatremia, left untreated, endanger the lives of patients through their involvement in the pathogenesis of some of the main leading causes of mortality and morbidity worldwide, cardiovascular disease.


Sodium (Na) is both an electrolyte and mineral. It helps keep the water and electrolyte balance of the body. It also has a role in nerves and muscles’ function. [1] In body fluids, Na is found in the ionized form (Na +). Sodium is predominating in the extracellular sector where it is the main cation, while potassium is the main cation in the intracellular space. This asymmetric distribution of electrolytes on either side of the cell membrane requires active exchange via Na +/K +-ATPase. The preponderance of sodium over other cations is stored in other body fluids: gastric juice, pancreatic juice, gallbladder, intestinal juice, cecal fluid, sweat, CSF. A relatively large amount of sodium is found in the cartilage and slightly less in the bones. Sodium in the skeleton represents 15-30% of the total amount of the body, an amount of up to 15-30% of it can be exchanged with that of extracellular fluids. The total amount of sodium in the bones increases with age, while the mobilized fraction decreases. This fraction is clinically important in that it is a useful reservoir for sodium loss and acidosis. [2]

Metabolism of Sodium

Sodium metabolism is regulated by the kidney through the interaction of the renin-angiotensin-aldosterone system, sympathetic nervous system, atrial natriuretic peptide, brain natriuretic peptide, effective circulating volume, and serum H2O content. H2O metabolism is tightly regulated by arginine vasopressin. [3] Most of the sodium in the body (approximately 85%) is found in blood and lymphatic fluid, sodium levels of the body are partially controlled by a hormone called aldosterone, secreted by adrenal glands. Aldosterone levels transmit to the kidneys when retaining sodium in the body, instead of passing it in the urine. The balance of sodium between the three spaces is made through the separation membranes, by diffusion together with other substances (water, K, amino acids, etc.) and by active processes with various speeds. The total amount of Na in the body is 3,500-4,500mEq, found in two osmotically inactive forms: 500mEq in connective tissue, cartilage and 1,400-1900mEq in bones, skin tissue and adipose tissue.  Around 30% of Na is osmotically active and participates in the development of voltage-osmoregulatory processes. In the blood, Na circulates in two forms: bound and in an ionic state, chemically active. The value represents a biological constant with tight variation limits hyponatremia 136mEq and hypernatremia 160mEq. Exceeding these limits is accompanied by serious conditions such as “noncommunicable diseases including hypertension and cardiovascular disease” [20] that, untreated, could become life-threatening. [4]

Dietary Intake of Sodium

Sodium is an essential nutrient found in salt and many foods (mainly processed and ready-made ones). Our bodies need a small amount of sodium to be healthy, but too much can lead to high blood pressure, a major risk factor for cardiovascular disease (stroke, heart disease, etc) and kidney disease. Sodium intake has also been linked to an increased risk of osteoporosis, stomach cancer and severity of asthma. It is recommended (referred to as Adequate Intake-AI) that people over the age of one year consume between 1000-1500 mg sodium per day. People aged 14 and over should not eat more than 2300 mg sodium per day, based on the 2015–2020 U.S. Dietary Guidelines, referred to as the Tolerable Upper Intake Level (UL). An adult sodium intake above 2300 mg per day is likely to pose a health risk.[5][20]

Table 1: Recommended Daily Intake of Sodium [5]

Healthy Adequate Intake (AI)


Upper Limit (UL)


Infants 0-6 months 120 mg/day No data
Infants 7-12 months 370 mg/day No data
Children 1-3 years 1000 mg/day 1500 mg/day
Children 4-8 years 1200 mg/day 1900 mg/day
Teens 9-13 years 1500 mg/day 2200 mg/day
Adults 14-50 years 1500 mg/day 2300 mg/day
Older adults 51-70 years 1300 mg/day  
Older adults over 70 years 1200 mg/day  
Pregnancy 1500 mg/day  

The 2020-2025 Dietary Guidelines for Americans recommend that Americans consume less than 2,300 milligrams (mg) of sodium each day as part of a healthy eating pattern. [6] About 70% of the sodium consumed comes from processed, ready-made and restaurant foods, so only a small amount of sodium or salt is added to cooking and meals. [7] Based on data showing that 500,000 deaths each year are related to high blood pressure and that the risk of CVD increases by up to 6% for each 1 gram increase in sodium intake per day, reducing sodium intake becomes a priority in prevention of thousands of deaths annually. [8][20]

Diet Rich in Salt [19]

  • Mixed dishes including pizza, sandwiches, burgers, burritos, and tacos;
  • Processed meats such as bacon, sausage, lunch meats and hotdogs;
  • Bread and rolls or grains that include sauces or seasonings that include salt;
  • Canned vegetables and soups or frozen dinners;
  • Snacks including chips, pretzels, and crackers;
  • Condiments including salad dressings.

It is recommended to look after sodium quantities in particular foods by reading the Nutrition Facts label. People should choose foods with less than 120 milligrams of sodium per serving.

Restriction of sodium intake can be made by consuming a variety of fruits and vegetables regularly in the diet. For frozen products, people should look for ones without added sauces or sodium and if choosing canned vegetables, a selection of low-sodium or no-salt-added items is a good idea.  In addition to this, another way is to limit the intake of highly processed foods and avoid added salt in meals. [19]

Sodium Disorders


Hyponatremia is a low sodium concentration in the blood. It is generally defined as a sodium concentration of less than 135 mmol/L (135 mEq/L), with severe hyponatremia being below 120 mEq/L. [9,10]

Common Causes of hyponatremia include: 

  • Hypovolemic (GI, renal, skin, blood fluid loss);
  • Euvolemic (syndrome of inappropriate antidiuretic hormone secretion (SIADH)/stress, adrenal insufficiency, hypothyroid, diet/intake);
  • Hypervolemic (CHF, cirrhosis, nephrotic syndrome).[11]

Signs and Symptoms of Hyponatremia

Symptoms depend on the degree of hyponatremia and velocity of progression from the onset. If the onset is <24-48h is called acute hyponatremia and is more likely to be symptomatic, whereas chronic hyponatremia (>24-48 h) is less likely to be symptomatic due to adaptation. In other words, normalization of brain volume through loss of cellular electrolytes within hours and organic osmolytes within days. [11] Symptoms can be absent, mild, or severe. Mild symptoms include headaches, nausea, and balance issues.  Severe symptoms include confusion, seizures, and coma. [12][13]

Complications are seizures, coma, respiratory arrest, permanent brain damage, brainstem herniation, death. In case of rapid correction of hyponatremia, there is a risk of brain cell shrinkage which can develop osmotic demyelination of pontine and extrapontine neurons. Untreated can be irreversible such as central pontine myelinolysis. [11]

Treatment of Hyponatremia

In case of mild hyponatremia (no symptoms) the main treatment would be fluid restriction. However, the treatment in case of moderate to severe hyponatremia (confused, seizures) are saline infusion with loop diuretics, hypertonic (3 percent) saline, checking serum sodium frequently and ADH blockers (conivaptan, tolvaptan). Correction of serum sodium should be less than 10–12 mEq/L in the first 24 hours or less than 18 mEq/L in the first 48 hours. Otherwise, there is a high risk of central pontine myelinolysis. [14]


Hypernatremia is a common electrolyte problem that is defined as a rise in serum sodium concentration to a value exceeding 145 mmol/L. It is a frequently encountered electrolyte disturbance in the hospital setting, with unappreciated high mortality. Understanding hypernatremia requires a comprehension of body fluid compartments, as well as concepts of the preservation of normal body water balance. The human body maintains a normal osmolality between 280 and 295 mOsm/kg via Arginine Vasopressin (AVP), thirst, and the renal response to AVP; dysfunction of all three of these factors can cause hypernatremia. [15] Common causes are inadequate H2O intake (elderly/disabled) or inappropriate excretion of H2O, diuretics, Li, and diabetes insipidus.[11]

Signs and Symptoms of Hypernatremia

The major symptom is thirst. The most important signs result from brain cell shrinkage and include confusion, muscle twitching or spasms. With severe elevations, seizures and comas may occur. [16] Values above 180 mmol/L are associated with a high mortality rate, particularly in adults. [17]

Treatment of Hypernatremia

Treatment of hypernatremia is based on salt restriction and administration of normal saline until the patient is hemodynamically stable. When the vitals are stable, it is recommended the administration of half-normal saline. Correction of serum sodium should be less than 12 mmol/L in 24 h drop in Na+ (0.5 mmol/L/h) due to risk of cerebral edema, seizures, death otherwise. [11]


A balanced lifestyle, based on maintaining a healthy sodium intake, leads to an equilibrium that helps maintain homeostasis and the well-being of the cardiovascular system. Further studies would emphasize the relationship between the amount of sodium administered/consumed and the response in the body that would facilitate the approach to nutrition and management based on sodium.


  1. accessed in November 2021
  2. accessed in November 2021
  3. Samir Patel, James M. HunterJr., in Essence of Anesthesia Practice (Third Edition), 2011; 192
  4. Munteanu Constantin, Iliuţã Alexandru Rolul sodiului în organism, Balneo-Research Journal, 2011; Vol.2, Nr.2, 70-74
  5. accessed in November 2021
  1. U.S. Department of Agriculture, U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025external icon, 9th ed. December 2020.
  2. Harnack LI, Cogswell ME, Shikany JM, Gardner CD, Gillespie C, Loria CM, et al. Sources of sodium in U.S. adults from 3 geographic regions external icon. Circulation. 2017;135(19):1775–83
  3. Palar K, Sturm R. Potential societal savings from reduced sodium consumption in the U.S. adult population external icon. Am J Health Promot. 2009;24(1):49–57
  4. Henry, DA (4 August 2015). “In The Clinic: Hyponatremia”. Annals of Internal Medicine. 163 (3): ITC1–19
  5. Chatterjee, Kanu; Anderson, Mark; Heistad, Donald; Kerber, Richard E. (2014). Manual of Heart Failure. JP Medical Ltd. p. 142
  6. Megan Drupals & Matthaeus Ware TORONTO NOTES 2021, 37th edition, Nephrology; 762-765
  7. Williams, DM; Gallagher, M; Handley, J; Stephens, JW (July 2016). “The clinical management of hyponatremia”. Postgraduate Medical Journal. 92 (1089): 407–11
  8. Williams, DM; Gallagher, M; Handley, J; Stephens, JW (July 2016). “The clinical management of hyponatremia”. Postgraduate Medical Journal. 92 (1089): 407–11
  9. Master the boards’ Step 3 Conrad Fisher, Nephrology; 654-655
  10. Saif A Muhsin, David B Mount Diagnosis and treatment of hypernatremia Best Pract Res Clin Endocrinol Metab 2016 Mar;30(2):189-203
  11. Lewis, J. L. (March 2013). “Hypernatremia”. Merck Manual of Diagnosis and Therapy. Medical Library Association.
  12. Ofran, Y.; Lavi, D.; Opher, D.; Weiss, T. A.; Elinav, E. (2004). “Fatal voluntary salt intake resulting in the highest ever documented sodium plasma level in adults (255 mmol L−1) a disorder linked to female gender and psychiatric disorders”. J. Intern. Med. 256 (6): 525–528.
  13. accessed in Nov 2021
  14. accessed in November 2021
  1. Wang YJ, Yeh TL, Shih MC, Tu YK, Chien KL. Dietary Sodium Intake and Risk of Cardiovascular Disease: A Systematic Review and Dose-Response Meta-Analysis. Nutrients. 2020;12(10):2934. Published 2020 Sep 25. doi:10.3390/nu12102934 

Journal of Vita Columbia Volume 2 Issue 1 – Clinical Nutrition

Calcium: An Overview of Metabolism and Homeostasis

January 18th, 2022
How to cite this article:

Azer M and Azer M. Calcium: An Overview of Metabolism and Homeostasis. 2022. Journal of Vita Columbia. 2(1).


Calcium is a mineral found in nature but it is also very vital for processes essential for life in the human body. The human body can’t produce it so it must be ingested. The active form, free ionized calcium in the body must be kept within a strict range otherwise the body begins to enter a diseased state. Whether hypocalcaemia or hypercalcemia, the diseased state of the body presents with several vague signs and symptoms that can lead a physician on a wild goose chase if you aren’t aware of what to look for. In this essay we explore calcium and its effects on the body in normal and abnormal states.


The human body uses many minerals to regulate and help in its many physiological actions. Calcium is one of the most abundant minerals in the body. The word calcium is derived from the word ‘calas’ which means lime in Latin, because it was used by the ancient Romans to prepare lime (CaO) since the first century (2).

The human body contains around 1-1.3 kg of calcium, stored mainly in bones (approximately 99%) and the remaining 1% is distributed as follows: 15% bound to anions, 40% bound to albumin, 45% circulates as free ionized calcium (the active form) (6) .

Calcium is needed in many vital processes in the body; muscle contraction, nerve conduction, blood coagulation, maintenance of cell membranes and release of hormones to name a few uses (2) . A good accumulation of calcium in the bones at early stages in life is the best prevention of age-related bone loss and fractures.

It’s easy to say it is vital to essential processes in the body, and to prattle off a few titles but what exactly does calcium do? Calcium controls nerve excitability (2). The effect is mainly on the peripheral neuromuscular mechanism. It plays a role in maintenance of the integrity of the skeletal muscles (2). It is very essential for maintaining the tone and contractility of cardiac muscles (2). Calcium also takes part in the formation of certain tissue and bones (2).

Metabolism of Calcium

Despite the importance of calcium to the body, it doesn’t produce calcium. we depend on enteral absorption of calcium, around 1000 mg of calcium is ingested daily in a balanced diet. Around 400 mg of that is absorbed through the GIT and the rest is excreted with the stool.

Calcium bioavailability represents the amount of calcium that actually absorbed rather than the amount of calcium in the food (1).  To understand this better, we can use examples; as dairy foods have 30% bioavailability which means if the food label mentions that milk has 300 mg of calcium per cup, the body will absorb around 100 mg of it. On the other hand, leafy green vegetables may have less calcium content but have more bioavailability, for example bok choy has 160 mg of calcium per cup and a high bioavailability of around 50%, that means about 80 mg of calcium will reach the body. (1)

Here is a problem however, some plants have substances that bind to calcium and hence decrease calcium bioavailability such as (oxalates and phytates). Spinach has the largest amount of calcium in all vegetables (around 260 mg per cup) however it is rich in oxalates that bind with calcium making a compound that can’t be absorbed in the GIT. This results in a decrease of the bioavailability to around 5%, so out of the 260 mg of calcium, only 13 mg is absorbed.

The information is not to avoid vegetables since they are rich in many other nutrients, but to organize meals properly, especially if calcium supplements are used. i.e. don’t consume calcium binding food like spinach with calcium supplements or food rich in calcium. (1)

Other factors that affect calcium absorption include following a vegan diet, consuming a large amount of proteins or bowel and digestive diseases (inflammatory bowel disease, lactose intolerance, etc. (7)

Table 1: Recommended Daily Intake of Calcium by Age-Group (8)

Life Stage Recommended Amount
Birth to 6 months 200 mg
 Infants  7–12 months 260 mg
Children 1–3 years 700 mg
Children 4–8 years 1,000 mg
Children 9–13 years 1,300 mg
Teens 14–18 years 1,300 mg
Adults 19–50 years 1,000 mg
Adult men 51–70 years 1,000 mg
Adult women 51–70 years 1,200 mg
Adults 71 years and older 1,200 mg
Pregnant and breastfeeding teens 1,300 mg
Pregnant and breastfeeding adults 1,000 mg

Calcium Level Regulation

The average range of serum calcium is 2.2-2.6 mmol/L in adults. The normal level of ionized calcium 1.17-1.3 mmol/L. Calcium level in plasma depends directly on the balance of bone mineral deposition and resorption, intestinal absorption, and renal excretion (6) . The hormones responsible for regulating these processes include Parathyroid hormone (PTH), 1,25-dihydroxyvitamin D, and calcitonin (6).

PTH is secreted by the parathyroid glands as a response to hypocalcaemia, the gland senses the decrease in calcium serum level and secrete parathyroid hormone, the results of which are evident within minutes through:

  1. increase calcium reabsorption through the kidneys
  2. increase calcium absorption in GIT
  3. increase bone resorption
  4. stimulate activation of vitamin D to calcitriol which increases calcium absorption by the intestines. (4)

Vitamin D is produced in the skin by the help of ultraviolet rays from the sunlight. It is then activated to its major circulating form (25(OH) D) and hormonal form (1, 25(OH) 2D) in the liver and kidney, respectively. Its main role is to facilitate intestinal calcium absorption, it also plays a role in bone growth and remodeling by osteoblasts and osteoclasts. Vitamin D has other roles in the body, including reduction of inflammation as well as modulation of such processes as cell growth, neuromuscular and immune function, and glucose metabolism. (5)

Calcitonin is produced from the parafollicular cells in the thyroid gland. It decreases the serum calcium level through:

  1. increases cellular uptake
  2. increases renal excretion
  3. increases osteoblastic activity in bones to build more cells taking more calcium. (4)

In general, parathyroid hormone and vitamin D have a more active role on bone metabolism and remodeling than calcitonin.

Pharmacologic Interactions with Calcium Homeostasis:

There are also many medications affect the level of ionized calcium in blood stream:

There are drugs that increase ionized calcium levels, such as (6): 

  •       Calcium salts
  •       Hydralazine
  •       Lithium
  •       Thiazide diuretics
  •       Thyroxine

There are also drugs that decrease ionized calcium levels, such as (6): 

  •       Heparin
  •       Citrate
  •       Intravenous lipids
  •       Epinephrine
  •       Norepinephrine
  •       Isoproterenol
  •       Alcohol
  •       Ethylenediaminetetraacetic acid


Outside of the normal range of Calcium we are in one of 2 diseased states, either hypo- or hypercalcemia.

Calcium deficiency is usually due to an inadequate intake of it, therefore when the calcium level drops, the body borrows some from the bones, to be returned to the bones from calcium supplied through the diet (2). If there’s still an inadequate supply of calcium, there will not be enough calcium available to be returned to bones to maintain strong bones and total body health (2).

There are many situations that cause hypocalcaemia: (16)

  • Hypoparathyroidism
  • Pseudo hypoparathyroidism
  • Vitamin D deficiency
  • Renal tubular disease
  • Acute pancreatitis
  • Magnesium depletion (decreased secretion and tissue response to parathyroid hormone)
  • Hungry bone syndrome
  • Septic shock
  • Hyperphosphatemia
  • Massive blood transfusion (> 10 units)

Symptoms of Hypocalcemia

Perhaps two of the most common hypocalcaemia manifestations are perioral numbness or tingling and heart palpitations (arrhythmia). There are, however, a plethora of manifestations that are also quite non-specific but that altogether point us towards a veritable diagnosis.

Muscle Cramping, numbness and tingling in the arms and legs, hyperreflexia, dry Skin, brittle nails, coarse hair, repeated candida infections, cataract, increased PMS symptoms and joint pain are all non-specific on their own but altogether point to hypocalcaemia in the differential diagnosis (2). It is tetany (paresthesia of fingers, feet and perioral region, spasm of facial muscles, carpopedal spasm), heart palpitations (arrhythmia) and osteoporosis (i.e., bone fractures) that force us to investigate a lack of calcium in the body as the primary cause of disease.

There are also of course the famous signs to diagnose hypocalcaemia, Chvostek sign, twitching of facial muscle after tapping on facial nerve, anterior to exterior auditory meatus. Also, Trousseau sign, carpal spasm after inflating blood pressure cuff to 20mmhg above systolic for 3 minutes. (15)

Treatment of Hypocalcemia

Treatment for hypocalcaemia is relatively simple, there are many kinds of calcium supplements.

  • Calcium gluconate used to treat conditions caused by low  calcium  levels such as  osteoporosis, osteomalacia and rickets. It is also used in hypoparathyroidism. (9)
  • Calcium chloride for arrhythmia, hypermagnesemia, calcium channel blocker overdose and beta blocker overdose (10).
  • Calcium acetate to treat hyperphosphatemia in end stage renal failure (11).
  • Calcium citrate used for primary osteoporosis prevention it also protects against renal stones by oxalate chelating and prevent its absorption through the intestine (12).
  • Calcium carbonate, antacid (tums) (13)


When total serum calcium exceeds 10.4mg/dl ( 2.6 mmol/l ) or ionized calcium is more than 5.2 md/dl (1.3 mmol/l). (14)

Some of the more common causes of hypercalcemia are hyperparathyroidism, vitamin D toxicity, malignancy (paraneoplastic syndrome) in breast cancer, lymphoma, prostate cancer, thyroid cancer, lung cancer, myeloma, and colon cancer). Also, many other diseases can be associated with hypercalcemia such as tuberculosis, sarcoidosis, leprosy and histoplasmosis. (14)

Less commonly, diseases like milk alkali syndrome, familial hypocalciuric hypercalcemia and some conditions like immobility and severe dehydration can cause hypercalcemia. (14)

Symptoms of Hypercalcemia

What should we be on the search for in hypercalcemia? As in hypo, most of the signs and symptoms are vague and non-specific: nausea and vomiting, constipation, abdominal pain, generalized aches, polyuria, muscle weakness, depression, confusion, lethargy and coma. (14)

Hypercalcemia can also lead to kidney stones up to kidney failure. Other complications include osteoporosis, dementia and cardiac arrhythmia which can be fatal.

Treatment of Hypercalcemia

Management of hypercalcemia depends on the severity of each case and whether it’s acute or chronic. Usually it starts with IV saline and diuretics (furosemide). The next step is bisphosphonates. Also hemodialysis or surgical removal of parathyroid glands can be used for refractory cases. (14)


Calcium is one of the most important minerals in the body, it is essential and vital for life. However it has to be within a specified range as too much or too little of the active form in the blood can be disastrous and possibly fatal. While most of the signs and symptoms of calcium imbalance in the body are vague there are specific warning signs to be on the lookout for as physicians and special tests to determine if calcium imbalance is the culprit.


  1. Calcium – The Nutrition Source., Harvard T.H. Chan – School of Public Health.,
  2. Piste,Pravina., Calcium and its Role in Human Body.,, January 2012.,
  3. Watson, Stephanie., Calcium: What you should know., WebMD -Vitamins and Supplements., June 2020.,
  4.  Lewis III, James L., Overview of Disorders of Calcium Concentration., Merck Manual – Professional Version., April 2020.,
  5. Vitamin D – Health Professional Fact Sheet., National Institutes of Health- Office of Dietary Supplements., August 2021.,
  6. Goldberg, Deborah., Calcium, Ionized., Medscape – Laboratory Medicine., Nov. 2019.,
  7. Mayo Clinic Staff., Calcium and calcium supplements: Achieving the right balance., Healthy Lifestyle – Nutrition and Healthy Eating., November 2020.,
  8. Calcium – Fact Sheet for Consumers., National Institutes of Health – Office of Dietary Supplements. March 2021.,
  10. Calcium Chloride (Rx) – Brand and other names., Medscape – Drug and Diseases.,
  11. Calcium Acetate (Rx) – Brand and other names., Medscape – Drug and Diseases.,
  12. Calcium Citrate (Rx) – Brand and other names., Medscape – Drug and Diseases.,
  13. Calcium Carbonate (Rx) – Brand and other names., Medscape – Drug and Diseases.,
  14. Lewis III, James L., Hypercalcemia. MSD Manual Professional version. April 2020.,