Diagnosis/Progress of Hyponatremia

There are three different types of hyponatremia, and based on the amount of fluid in the cells, we can differentiate between the different types of hyponatremias.  The three types that we can diagnose are all a type of hypotonic hyponatremia.  They are: hypovolemic, euvolemic, and hypervolemic hyponatremia (1).  In all of theses cases, the blood level of sodium decreases to below 135 mEq/L (which is below the normal range of serum sodium).  Hypovolemic hyponatremia is presented with a depletion of ECF (extracellular fluid).  Since this is not easily detectable, the best way to detect hypovolemic hyponatremia is through patient history, physical examination, and laboratory results (1).  The symptoms that the patient may have include vomiting, diarrhea, orthostatic blood pressure decrease, increased pulse, and signs of dehydration (decreased skin turgor and dry mucous membranes) (1).  Laboratory signs include elevations of BUN, creatinine, and uric acid (1).   However, the laboratory signs are non-specific and can apply to other diseases.  Euvolemic hyponatremia occurs because of the high prevalence of SIADH.  It is diagnosed primarily from the patient's history, physical examination, and laboratory results (1).  Laboratory results that are indicative of euvolemic hyponatremia include a low BUN and a low serum uric acid level.  Measuring urine sodium is the most helpful in diagnosing euvolemic hyponatremia.  Hypervolemic hyponatremia is a detectable increased ECF volume.  This is usually caused by the inability of the body to excrete fluid.  With the buildup of fluid in the body, the body can be volume overloaded, thus causing hypo-osmolarity.  The diagnosis of fluid excess from hypervolemic hyponatremia is made through the patients history, physical examination, and laboratory results.  Physical examination can help detect patients with signs of fluid overload (edema, ascites, and pulmonary edema).  Laboratory results to detect hypervolemic hyponatremia include elevation of plasma levels of brain natriuretic peptide and a low urine of fractional sodium excretion due to the activation of the renin-angiotensin-aldosterone system.  In acute hyponatremia, one of the deadliest complications is brain herniation. Symptoms can progress from headache, nausea, vomiting, or confusion to seizures, respiratory arrest, and/or death.  They can also progress to a permanent vegatative state as a complication from severe cerebral edema (1).  These symptoms happen the most to postoperative patients, patients with water intoxication brought on by endurance exercises (like marathons), or use of drugs such as eccstasy (1).  Who knew hyponatremia could be so scary?

Brain Herniation 

Works Cited

1)  Verblis, J., Goldsmith, S., Greenberg, A., Korzelius, C., Schrier, R., Sterns, R., & Thompson, C. (2013). Diagnosis, Evaluation, and Treatment of Hyponatremia: Expert Panel Recommendations. The American Journal of Medicine, 126(10), S1-S42. Retrieved April 22, 2015, from http://www.amjmed.com/article/S0002-9343(13)00605-0/fulltext

Hyponatremia Etiology/Pathophysiology

Hyponatremia's etiology and pathophysiology are very interesting.  First of all, I will talk about the etiology of hyponatremia (how it's caused).  Before that though, I must reiterate from my previous blog post:  there are two types of hyponatremia; dilutional and depletional hyponatremia.  Dilutional hyponatremia is just what it sounds like.  There is too much fluid in your blood, which decreases the concentration of sodium in the blood to less than 135 mEq/L.  This is much like the effect of pouring distilled water into salt water, making the water less "salty".  Depletional hyponatremia is when the body loses too much sodium via fluid loss.  Prime examples include urine and sweat.  People who are most at risk of this are people who exercise too much, losing too much sodium through sweat.  Most people with hyponatremia have resided/reside in a healthcare setting.  "Surely, it must be some kind of disease that causes the sodium level to go down" you may think.  That is not the case at all.  One of the biggest causes of hyponatremia is iatragenic (caused by the healthcare professional).  Many times, there are co-morbidities associated with hyponatremia.  Hyponatremia serves as a marker for heart and liver diseases.  It is also associated with kidney injury, brain tumors, and brain hemorrhaging (1). In a study, the hospital mortality rate for patients with hyponatremia was 6.1% as compared to 2.3% with non-hyponatremic patients (1).

Mortality vs. Serum Sodium

With the chart shown above, we can see that mortality percentage peaks at patients with serum sodium at 115 to 124 mEq/L.  Several points of evidence suggests that hyponatremia is rarely a cause of death, but rather a marker for  the severity of the underlying disease (1).  "(1) once sNa falls below 120 mEq/L, mortality rate does not seem to increase as the severity of hyponatremia worsens; in fact the trend is in the opposite direction; (2) deaths in patients with sNa <120 mEq/L were associated with serious comorbidities and were mostly attributable to conditions other than hyponatremia; (3) neurologic symptoms attributable to hyponatremia were uncommon among fatal cases, and deaths attributable to neurologic complications were rare. (1)"

Fatal cases with uncorrected hospital-acquired or hospital-aggravated hyponatremia

Age/Gender	Admission SNa (mEqL)	Lowest SNa (mEq/L)	SNa at Death (mEq/L)	Day of Death	Clinical Course	Comfort Care?	Charlson Score
66/M	145	114	114	27	Metastatic carcinoma, cardiac arrest, respiratory failure, anoxic brain damage, acute kidney injury, refractory shock. First SNa <120 mEq/L 4 days before death	Yes	11
67/M	139	115	115	163	Sepsis with several months in hospital with irreversible multiorgan failure; first sNa <120 mEq/L on day 155, 8 days before death	Yes	5
63/M	138	117	117	16	Metastatic carcinoma, acute kidney injury, acute respiratory failure. First SNa <120 mEq/L 1 day before death	Yes	11
87/M	136	118	123	24	ESRD. Comfort care on admission.	Yes	4
65/M	132	118	118	11	End-stage liver disease, sepsis, multiorgan failure. First sNa <120 mEq/L on day of death	Yes	5
65/M	131	119	119	11	Cardiogenic shock. First sNa <120 mEq/L 1 day before death	Yes	4
55/M	124	119	122	12	End-stage heart disease, acute kidney injury	No	7
54/F	124	119	122	4	End-stage lung disease	Yes	3
83/M	120	118	123	7	End stage heart disease	No	8
63/M	121	119	122	2	Advanced lung cancer	No	7

As you can see from this table, almost all patients who had hyponatremia died of an underlying progressive illness (1).  We can conclude that many cases of hyponatremia can be directly linked to or tied to another disease.  Sure, it's possible to die from hyponatremia, but most of the time, it's more complicated than that. 

Works Cited:

1) Chawla, A., Sterns, R., Nigwekar, S., & Cappuccio, J. (2011). Mortality and Serum Sodium: Do Patients Die from or with Hyponatremia? Clinical Journal of the American Society of Nephrology, 960-965. Retrieved April 17, 2015, from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3087791/#B18

Epidemiology of Hyponatremia 

Hyponatremia in reality is not too common of a disease, especially in the U.S.  With the abundance of nutrients and food, there is one place where hyponatremia is extremely prevalent, and that is in the healthcare setting (e.g hospitals, retirement homes, etc.). In the hospital setting, the incidence of hyponatremia lies at around 15% of patients.  67% of cases of hyponatremia are iatrogenic, which means that the state of hyponatremia was brought on by the healthcare workers themselves (1).  The risk of hyponatremia increases with age (1).  Incidences have been reported from 7-51% in geriatric patients, with many of them occuring in long term care centers (2).  Why is this even important?  Sodium plays an important role in the body's water regulation along with many other important bodily functions such as muscle and nerve function.  Without sodium, the body will not be able to properly function.  It is also important to note that there is an association between hyponatremia, heart failure, pulmonary tuberculosis, child diarrhea, and heart attacks (1).  This is important because even though it doesn't seem like hyponatremia is as life-threatening as something.... say like cancer, aids, or heart attack, it is still very important to monitor serum sodium levels.  Even slight hyponatremia increases the risk of death, so with immediate intervention, lives can be saved.

Hypnatremia and Hospital Mortality

Hyponatremia occurs in the hospital setting the most often and does not have a race/ethnicity preference. Outside of the hospital however, hyponatremia is prevalent in people who are participating in physical activity and sweat a lot.  Examples include marathon runners who lose lots of water, along with salt (sodium and chloride).  To remedy this, it is important to drink fluid with electrolytes (such as gatorade), along with not overdrinking water.  Just drinking the right amount is enough.  Always be careful to take everything in moderation, including water!

Works Cited 

1) Blevins, L. (2013, March 5). Hyponatremia: The Endocrinologist's Role in Improving Patient Outcomes. Retrieved April 9, 2015, from https://www.aace.com/sites/all/files/blevins_hyponatremia_ss2013AM.pdf

2) Verbalis, J., Goldsmith, S., Greenberg, A., Korzelius, C., Schrier, R., Sterns, R., & Thompson, C. (2013). Diagnosis, Evaluation, and Treatment of Hyponatremia: Expert Panel Recommendations. American Journal of Medicine, 126(10), 42-42. Retrieved April 8, 2015, from http://www.amjmed.com/article/S0002-9343(13)00605-0/abstract

Hyponatremia

Welcome to the hyponatremia blog! Where we talk all things relating to not having enough sodium in your body!  How little sodium do you need in order not to be hyponatremic?  You would need 135 mEq/L of sodium in you blood to be considered hyponatremic.  "Daily incidence and prevalence of hyponatremia averaged 0.97% and 2.48% respectively.  Two thirds of all hyponatremia was hospital acquired." (Anderson, Chung, Kluge, and Schrier 2015, pp. 01)  How would one feel if you don't have adequate sodium in the body?  This depends.  There are two types of hyponatremia: dilutional and depletetional.  Dilutional hyponatremia is when there is too much fluid in the body, causing the concentration of sodium in the body to go down.  Imagine having a cup of water and adding three tablespoons of salt.  Then, add 5 cups of water.  There would be less salt compared to water.  That is dilutional hyponatremia.  Depletional hyponatremia is simple.  Too much sodium is excreted from your body, most likely via urine, causing your sodium concentration in your blood to go lower than 135 mEq/L.  According to Mayoclinic, the general signs and symptoms of hyponatremia include, nausea and vomiting, headache, confusion, loss of energy/fatigue, restlessness along with irritability, muscle weakness/spasms/cramps, seizures, and coma.  Here is a video that goes into great depth explaining the differences between dilutional and depletional hyponatremmia: 

Hyponatremia Video:

There are many causes of hyponatremia.  These are: Medications (such as diuretics), congestive heart failure (causes fluid accumulation, thus dilutional hyponatremia), symdrome of inappropriate anti-diuretic hormone (high levels of anti-diuretic hormone causes water retention, thus dilutional hyponatremia), chronic/severe vomiting or diarrhea (Causes your body to lose sodium; depletional), drinking too much water (dilutional), hormonal changes, and recreational drugs (ecstasy). 

Treatment for hyponatremia include fluid restriction, isotonic IV fluid, and medications to manage the signs and symptoms of hyponatremia.  There are also diuretics if your body has too much water, diluting the sodium.  

Remember, the greatest things to remember in preventing hyponatremia is to have adequate water intake.  This means 2.2 liters per day for women and 3 liters for men.  Drink no more than 1 liter per day!  If needed, drinks with electrolytes can help prevent sodium loss, such as Gatorade or Powerade (Martel 2012)

Works Cited

1) Martel, J. (2012, July 2). Low Blood Sodium (Hyponatremia). Retrieved April 2, 2015, from http://www.healthline.com/health/hyponatremia#Overview1

2) Anderson, R., Chung, H., Kluge, R., & Schrier, R. (1985, February 1). Hyponatremia: A Prospective Analysis of Its Epidemiology and the Pathogenetic Role of Vasopressin. Retrieved April 2, 2015, from http://annals.org/article.aspx?articleid=699425

3) Staff, M. (2014, May 28). Hyponatremia. Retrieved April 2, 2015, from http://www.mayoclinic.org/diseases-conditions/hyponatremia/basics/causes/con-20031445