motorola
Forum Extremist
Topics: 66
Posts: 416
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i find myself always confused with this term TTKG. found this explanation simple enough:
Definition
• A calculated measurement which estimates the tubular fluid potassium concentration at the end of the
cortical collecting tubule, the site responsible for most of potassium secretion
• In simplest terms, think of the TTKG as a rough measurement of aldosterone activity in the kidney
• TTKG = 8-9 in normal subject on a normal diet
Practical Application
• HYPERKALEMIA (TYPICALLY PERSISTENT HIGH K+)
♦ Use the TTKG to determine if high K+ is from low aldosterone states or from decreased effective circulating volume (in CHF, etc.)
♦ In low aldosterone states, K+ in the cortical collecting tubule should be low and thus the TTKG should be low
O If hypoaldosterone state, TTKG < 5
O If decreased ECV, TTKG > 7
• HYPOKALEMIA (PERSISTENT)
♦ Use the TTKG to determine renal vs. non-renal loss of potassium
♦ If loss is renal, assume hyperaldosterone state and thus K+ at the cortical collecting duct should be high and thus the TTKG should be high
O If renal loss of K+, TTKG > 7
O If non-renal loss, TTKG < 5 (should be hypoaldo from low K+)
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