While there was no significant difference between baseline blood measurements of the two groups in terms of kidney function tests and electrolytes , following 3 weeks of the study , the mean serum potassium level decreased from 4.9 0.8 mEq/L to 4.5 0.5 mEq/L in the LMW heparin group ( P = .001 ) ; however , there was no change in the mean serum potassium level in those who continued to receive their usual dose of UF heparin .