A 32 yr old woman was admitted to the hospital following 2 1/2 days of severe vo

Question

A 32 yr old woman was admitted to the hospital following 2 1/2 days of severe vomiting. Before this episode, she was repeatedly well. Physical findings revealed decreased skin turgor and dry mucous membranes. Admission study results were as follows:

Serum: Urine:

Na+ 129 mmol/L Na+ 8 mmol/L

K+ 5.0 mmol/L Ketones trace

Cl- 77 mmol/L

HCO3- 9 mmol/L

Osmolality 265 mOsm/kg

a. What is the cause for each abnormal plasma electrolyte result?

b. What is the significance of the urine sodium and serum osmolality results?

Explanation / Answer

Acceptable or standard rang;-

serum sodium: 135–145 mmol/l

serum potassium: 3.6–5.4 mmol/l

serum chloride: 98–108 mmol/l

serum bicarbonate: 18–24 mmol/l

osmolality (calculated) 280–300 mosm/kg

serum Na+ is a bit less.

causes:-

Hyponatremia is more often a problem in older adults. It can be caused by:

the serum K+ level is under the standard range.

the serum Cl- is less then the standard level(called hypochloremia)

causes;-

It rarely occurs in the absence of other abnormalities. Its sometimes associated with hypoventilation. It can be associated with chronic respiratory acidosis. If it occurs together with metabolic alkalosis (decreased blood acidity) it is often due to vomiting. It is usually the result of hyponatremia or elevated bicarbonate concentration. It occurs in cystic fibrosis.

the serum HCO3- is less then the standard level.(called metabolic acidosis)

causes:-

Metabolic acidosis occurs when the body produces too much acid, or when the kidneys are not removing enough acid from the body.

serum osmolality range is also less.

cause:-

If you drink too much water, the concentration of chemicals in your blood decreases. When serum osmolality decreases, your body stops releasing ADH. This increases the amount of water in your urine. It keeps too much water from building up in your body (overhydration).

Urine sodium:-normal urine sodium values are generally 20 mEq/L in a random urine sample and 40 to 220 mEq/L per day (mEq/L/day)

this lady has a very less concentration of urine sodium.

causes:-

urine ketone:-..having urine ketone is traces is absolutely normal.

significance of serum osmolalility

A serum osmolality test measures the amount of chemicals dissolved in the liquid part (serum) of the blood. Chemicals that affect serum osmolality include sodium, chloride, bicarbonate, proteins, and sugar (glucose).This test is done on a blood sample taken from a vein.

significance of urine sodium

Urine sodium is a measurement of the level of sodium in the urine.The urine sodium is expressed as a concentration (such as milimoles per liter). The result must therefore be interpreted in the context of the degree of urine concentration present. Alternatively, the urine sodium can be standardized to the excretion of creatinine using a formula such as the fractional excretion of sodium (FENa).

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