MODULE 4 KNOWLEDGE CHECK
• Question 1
1 out of 1 points
A 67-year-old Caucasian woman was brought to the clinic by her son who stated that his
... [Show More] mother had become slightly confused over the past several days. She had been stumbling at home and had fallen once but was able to ambulate with some difficulty. She had no other obvious problems and had been eating and drinking. The son became concerned when she forgot her son’s name, so he thought he better bring her to the clinic.
PMH-Type II diabetes mellitus (DM) with peripheral neuropathy x 20 years. COPD. Depression after death of spouse several months ago
Social/family hx - non contributary except for 30 pack/year history tobacco use.
Meds: Metformin 500 mg po BID, ASA 81 mg po qam, escitalopram (Lexapro) 5 mg po q am started 2 months ago
Labs-CBC WNL; Chem 7- Glucose-92 mg/dl, BUN 18 mg/dl, Creatinine 1.1 mg/dl, Na+120 mmol/L,
K+4.2 mmol/L, CO237 m mol/L, Cl-97 mmol/L.
The APRN refers the patient to the ED and called endocrinology for a consult for diagnosis and management of syndrome of inappropriate antidiuretic hormone (SIADH).
Question:
Define SIADH and identify any patient characteristics that may have contributed to the development of SIADH.
Selected Answer: SIADH has high levels of the hormone ADH without the normal physiologic stimuli to release it. ADH increases the water reabsoprtion by the kidneys. This causes an expansion of extracellular fluid volume that leads to dilutional hyponatremia (low serum sodium), hypoosmolarity, and urine that is concentrated. It is caused by the ectopic production of ADH by tumors, such as small cell carcinoma of the duodenum, stomach, and pancreas, cancers of the bladder, prostate, and endometrium, lymphomas, and sarcomas. The patient is taking an antidepressant, Lexapro, which can cause SIADH. Hypoglycemic medications can also cause this condition. This patient has hyponatremia which results from retaining water that would normally be excreted in urine. Hyponatremia causes confusion as sodium levels drop.
Correct Answer:
SIADH is a group of symptoms that occurs when antidiuretic hormone (ADH, arginine vasopressin) is secreted in the absence of osmotic or physiologic stimuli. These stimuli include: Increased serum osmolality, decreased plasma volume, and hypotension. A decrease in plasma osmolality normally inhibits ADH production and secretion. SIADH is characterized by fluid retention, dilutional hyponatremia, hypochloremia, concentrated urine, and lack of intravascular volume depletion. SIADH is characterized by normal to increased blood volume in normoproteinemia, nonedematous, and hyponatremic patients with normal renal and endocrine function. ADH regulates the body's water balance. It is synthesized in the hypothalamus and stored in the posterior pituitary gland. When released into the circulation, it acts on the kidney's distal tubules and collecting ducts, increasing their permeability to water. This decreases urine volume because more water is being reabsorbed and returned to the circulation. It also serves to produce more concentrated urine.
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