Clinical Aspects of Hyponatremia

Question 1

What type of patients are linked with volume status issues

Answer 1

Hospitalized and elderly patients as well as patients with CHF and GI disturbances, burns, and sweating

Question 2

Medications that can cue us in to volume issues in our patients

Answer 2

Thiazides, nicotine, NSAIDs, morphine

Question 3

Lab findings for hyponatremia

Answer 3

plasma osmolality (usually reduced <100mOsmol/L if max dilute urine)

Urine sodium (fractional excretion of sodium U(Na)/P(Na)/U(Cr)/P(Cr))

Acid/base and Potassium status

Question 4

Remember, hyponatremia is not a disease, it is a ___ ___.

Answer 4

Remember, hyponatremia is not a disease, it is an “electrolyte sign”

Question 5

Measurement of serum osmolarity to rule out _____.

Answer 5

Measurement of serum osmolarity to rule out pseudohyponatremia

Question 6

What volumes are affected by hypovolemic hyponatremia

Answer 6

Effective art. volume depletion

True volume depletion (TBNa>TBW)

Question 7

Hormone levels associated with hypovolemic Hyponatremia

Answer 7

ADH Level elevated

Hypoaldosterone (inc. vascular reactivity and Na+ reabsorption)

Question 8

We associate these things with hypovolemic hyponatremia

Answer 8

Thiazide diuretics
GI losses (vomit, diarrhea)
Sweating
Burns

Question 9

What is Euvolemic Hyponatremia?

Answer 9

Euvolemic Hyponatremia (volume looks okay but hyponatremic→ compulsive water drinkers)

Question 10

Hormones associated with euvolemic hyponatremia

Answer 10

Increased ADH activity

Question 11

We associate these with euvolemic hyponatremia

Answer 11

Other clinical: pulmonary lesions, pain, CNS lesions, nonpituitary sources: tumor, granulomatous disease, exogenous administration

Question 12

Volume shifts with euvolemic hyponatremia

Answer 12

effective art. volume normal (initially elevated)

Question 13

We often refer to euvolemic hyponatremia as a syndrome of inappropriate ADH secretion. What causes this?

Answer 13

syndrome of inappropriate ADH secretion

drugs: nicotine, morphine, clofibrate, SSRIs, vincristine, cyclophosphamide

Question 14

These drugs elevate the activity of ADH

Answer 14

Drugs: tolbutamide, chlorpropamide, methylxanthines, NSAIDs (ecstasy?)

Question 15

This hyponatremic volume issue is known as a diagnosis of exclusion

Answer 15

Euvolemic

Question 16

Hormones related to hypervolemic hyponatremia

Answer 16

ADH level elevated

Question 17

Volume findings for hypervolemic hyponatremia

Answer 17

Effective art. volume depletion

Question 18

We associate these clinical findings with hypervolemic hyponatremia

Answer 18

Edematous states: CHF, Cirrhosis, nephrotic syndrome, pregnancy

Question 19

Compare total body sodium and volumes between the three subtypes.

Answer 19

Hypovolemic: decreased total body sodium accompanied by a decrease in the normal amounts of body water

Euvolemic: increased total body water with normal total body sodium.

Hypervolumic (like the movie Supersize Me): increase in both total body water and total body sodium, with the increase in TBW exceeding that of sodium.

Question 20

The physiology of Hypovolemic

Answer 20

ADH is physiologically secreted in response to low effective arterial volume and perfusion pressure. Tubular filtrate delivery distally is limited, due to GFR reduction, increased proximal Na reabsorption due to sluggish intra-tubular flow, and TGF. The result is that both H20 and Na excretion are reduced, but relatively more water is retained due to ADH effect.

Question 21

Physiology of euvolemia

Answer 21

There is either inappropriate ADH secretion, ADH sensitivity, or another situation which limits the ability to maximally dilute the urine. Patients often have a relatively normal to high urinary sodium excretion once they have achieved steady state.

Question 22

Physiology of hypervolemia

Answer 22

Effective arterial volume is perceived (by brain and kidneys) to be low, and although there is overall water and Na overload, the kidney behaves as if the total organism were hypovolemic. ADH is inappropriately active.

Question 23

Hypovolemic causes

Answer 23

renal losses: diuretics (thiazides), cerebral salt wasting, salt wasting nephropathy, mineralocorticoid insufficiency, bicarbonaturia, glycosuria, ketonuria

extrarenal losses: GI (vomiting, diarrhea), third spacing, sweat (endurance exercise)

Question 24

Causes of Euvolemic issues

Answer 24

SIADH
tumor-related ADH-like peptides

Pituitary disorders (several patterns exist), drugs, pain, lung disorders, thyroid/adrenal insufficiency OR

decreased solute intake and subsequent decreased excretion (beer potamia, low protein diet)

Question 25

Conditions of hypervolemic states

Answer 25

Edematous states: CHF, cirrhosis, nephrotic syndrome, renal failure (water is outside of vascular space so baroreceptors think that you’re hypovolemic)

Question 26

*Remember, ___ is controlled by volume status and this supercedes ____ sensitivity.

Answer 26

*Remember, ADH is controlled by volume status and this supercedes tonicity sensitivity.

Question 27

How do we treat the different types of volume changes?

Answer 27

Hypovolemic
IV normal saline
Brisk water diuresis

Euvolemic
Treatment of underlying cause

Hypervolemic
ACE inhibitors

Question 28

When do we want to concentrate the urine vs. dilute it?

Answer 28

Maximum diluting capacity is 50-100 mOsm/Kg. In hyponatremia, it is appropriate to maximally dilute the urine unless there is some other physiologic or pathophysiologic process active.
Maximum concentrating capacity is 900-1400 mOsm/Kg.

In hypernatremia, it is appropriate to maximally concentrate the urine–unless some other process (physiologic or pathophysiologic process) is active. The elderly should not get more than 500-700 mOsm/Kg

Question 29

Use of hypertonic saline is for the treatment of ________ in order to:

Answer 29

Use of hypertonic saline is for the treatment of acute symptomatic hyponatremia to alleviate symptoms only

Question 30

Issue with using hypertonic saline in a hyponatremic patient.

Answer 30

Known to be highly unpredictable due to rapid changes in the physiology; should be monitored every 2-4 hrs.