Hyponatremia: Case Description, SOAP Note and the Summary

Access: LimitedShow Details
  • This Doc can be read by: Anyone
  • This Doc can be edited by: The Doc author only
  • Comments are visible to: Anyone
  • Comments can be posted by: Logged-in Users
  • History can be viewed by: Anyone
Hide Details

Mrs. L is a 60-year-old woman who comes to see you for a follow-up of her hypertension. She only complains of mild fatigue. On physical exam, her BP is well controlled at 126/84 mm Hg. Routine chemistries reveal a serum sodium of 128 mEq/L. Her potassium and other electrolytes and creatinine are normal. Her glucose is 108 mg/dL and BUN is 28 mg/dL. Urine specific gravity is 1.025. Serum osmolality is 278 mOsm/L.

Mrs. L denies any history that suggests volume loss (vomiting, diarrhea, or excessive perspiration). She denies symptoms suggestive of hypervolemia such as edema, dyspnea on exertion, or orthopnea. Furthermore, she has no history of any diseases associated with hypervolemic states (HF, cirrhosis, renal failure, or nephrotic syndrome). On physical exam, BP is normal with no significant change going from lying to standing. There is no pretibial or pedal edema. Cardiovascular exam reveals no JVD or S3 gallop. She has no crackles on lung exam and there are no signs of ascites (bulging flanks, shifting dullness).

Mrs. L’s urine sodium concentration is 60 mEq/L.

Following a 1 L normal saline challenge, Mrs. L’s urinary output does not rise significantly. A repeat serum sodium 4 hours later is 126 mEq/L.

Past medical history: Hypertension treated with amlodipine. Social history: 40-pack-year history of smoking. Alcohol use is minimal. Mrs. L denies any drug use. Review of systems positive only for a cough that has been present over the last 1–2 months. Her TSH is 2.3 milli-international units/L (normal < 4.0 milli-international units/L).

The urine osmolality is 480 mOsm/L. The serum osmolality is 266 mOsm/L.

The serum cortisol level following 250 mcg of corticotropin is 800 nmol/L.

A chest film reveals a 5-cm pulmonary mass adjacent to the right hilum. Bronchoscopy and biopsy confirms small cell carcinoma of the lung. Mrs. L is referred to medical oncology. Her hyponatremia is controlled with free water restriction.


Subjective: 60 y/o female with a h/o HTN, 40-pack-year smoking complains of mild fatigue. Pt has a cough from the last 1-2 months. Denies of vomiting, diarrhea or excessive perspiration, edema, dyspnea on exertion or orthopnea. No history of heart failure, cirrhosis, renal failure or nephrotic syndrome. She is taking amlodipine for HTN. Pt’s alcohol use is minimum and denies any use of drug.

Objective: BP: 126/84, no significant change in going from lying to standing

No signs of pretibial or pedal edema, JVD, S­­3 gallop or ascites           

No crackle was noticed during the lungs exam                                 

Serum sodium: 128 mEq/L           

Potassium, creatinine and other electrolytes are normal.       

Glucose: 108 mg/dL                           

BUN: 28 mg/dL                                                                                                                                  

Urine specific gravity: 1.025                                                        

Serum osmolality: 278 mOsm/L                          

Urine sodium concentration: 60 mEq/L                                   

Mrs. L’s urinary output does not rise significantly, following a 1 L normal saline challenge. A repeat serum sodium 4 hours later is 126 mEq/L                                  

TSH: 2.3 milli-international units/L           

Urine osmolality: 480 mOsm/L                                                                                                  

Serum osmolality: 266 mOsm/L                                                                                              

Serum cortisol level following 250 mcg of corticotropin is 800 nmol/L

Assessment: Pt has SIADH, which led her to have hyponatremia, and her recent cough and long history of tobacco use indicate an underlying pulmonary etiology. A chest film revealed a 5-cm pulmonary mass adjacent to the right hilum. Bronchoscopy and biopsy confirmed small cell carcinoma of the lung.

R/O primary adrenal insufficiency, pituitary disease and primary hypothyroidism   

Plan: Referred to medical oncology

Control hyponatremia with free water restriction                                  

Summary: I was not quite familiar with hypo/hypernatremia, but I learned a lot about these abnormalities from this chapter. Hyponatremia occurs when someone has low sodium level in their blood, and hypernatremia is opposite of that; that is, hypernatremia is when someone has high concentration of sodium in their blood. Some common causes of hyponatremia are heart failure, diarrhea, use of diuretics, renal disease and the syndrome of inappropriate ADH secretion (SIADH). Patients usually complain of nausea, headache, muscle cramps, fatigue and confusion. The diagnosis includes doing a history and physical, and paying attention to the history of cancer, cardiac, pulmonary, neurologic, gastrointestinal, endocrine and renal histories. The patients might need to be tested for urine osmolality, serum osmolality and urine sodium level. The main treatment for hyponatremia is the restriction of fluid, and the patient might be given saline; nonetheless, the treatment mainly depends on the patient’s condition. Some patients might need immediate treatment or some might need different types of treatments. The patients might also be given medication to control the signs and symptoms of hyponatremia, such as, nausea or headache.

In Mrs. L’s case, although nothing can really be diagnosed from her history, she has an elevated urine osmolality and the serum osmolality is low, which indicate the possibility of her having SIADH. Also, her tobacco use and recent cough suggest that she might have SIADH from a lung cancer. SIADH often requires the treatment of underlying disease. Additionally, her complain of fatigue and lack of response to saline showed that she might have euvolemic hyponatremia. Furthermore, the elevated urine sodium remains consistent with her being euvolemic. She denied having edema, dyspnea on exertion, orthopnea, JVD, S3 gallop, crackles or ascites, which suggested that she is not hypervolemic; and, there was no sign of hypotension, tachycardia or orthostatic hypotension, which implied that she is hypovolemic. We could suspect that she has primary adrenal insufficiency; however, she reported that, for hypertension, she is being treated with amlodipine, which is a calcium channel blocker, and her blood glucose and potassium are normal, which rules out the possibility of her having hyperglycemic hyponatremia and it also makes the diagnosis for primary adrenal insufficiency to be less likely. Also, since her corticotropin stimulation test was normal, we were able to rule out the possibility of primary adrenal insufficiency. Additionally, her TSH was normal; and, thus, we could rule out hypothyroidism, as well.

As her chest film shows a 5-cm pulmonary mass adjacent to the right hilum, and bronchoscopy and biopsy confirm small cell carcinoma of the lung, Mrs. L is referred to medical oncology; and her hyponatremia will be controlled with free water restriction.





Working on this SOAP note was a great learning experience since it gave me an overview of what I will be doing once I start working as a Physician Assistant. It is a crucial skill that everyone, in this field, must acquire. My case was a patient with hyponatremia. Although I have heard of hyponatremia before, I did not have a good understanding of this condition. This case and the SOAP note helped me gain a deeper understanding of this condition, such as, learning different causes, types of hyponatremia, ways to diagnose and different types of treatments; and going through this case helped me see how to diagnose this disease and what to do when a patient has hyponatremia. It is hard to diagnose a condition unless we see the patient, but I tried my best with the information that was provided to me. As of now, when we go for hospital visits, we are required to write a full history and physical; however, when we start working, we will have to write a lot of SOAP notes which will be supported by the H and P of the patients. I enjoyed writing the SOAP note because it is very brief and relevant to the patient’s current conditions. During this exercise, we were provided with all the information and we just made the SOAP note from those information; however, now, my goal is to learn how to make a SOAP note, specifically how to reach a differential diagnosis, from the information that I collect from the patients.