11.   Obviously, careful monitoring of the serum phosphate level is appropriate.

12.   Renal disease and a variety of other diseases have not been shown to increase serum ferritin levels.

13.   The drug has first-order kinetics only at lower serum levels.

14.   The drug selected for monotherapy is then added and appropriate dosage adjustment made to attain therapeutic serum levels.

15.   The serum calcium level should occasionally be checked.

16.   The serum potassium level is sometimes helpful in determining acid-base status.

17.   They usually occur at serum levels above the recommended therapeutic range.

18.   The level of IgG and IgA anti-granulocyte antibodies did not correlate to the total serum levels of IgG and IgA.

19.   It appears that a decrease in parasite-specific immune responses occurs following elevation of serum prolactin levels.

20.   In fact, it has been calculated that even standing outdoors naked all day in Boston in winter would not result in the recommended serum levels of vitamin D.