What does the term ‘TTKG’ mean and how do you calculate it? What assumptions are necessary for the formula to be valid?
Consider this case:
A 42 year old male with HIV is admitted with PCP pneumonia. They are treated with high dose Septra. On day 5 of admission, the following results are noted:
Serum K = 6 mmol/L
Serum osmolality = 300 mosmol/L
Urine osmolality = 480 mosmol/L
Urine K = 20 mmol/L.
In the preceding patient with hyperkalemia, calculate the TTKG. What does this tell you about their ability to excrete potassium? Can you explain why this is happening?