Set 10 of 10 · mcg/kg/min
mcg/kg/min Calculation Practice
Critical care drips, such as vasoactive drugs, are often prescribed in micrograms per kilogram per minute (mcg/kg/min). The pump still runs in mL/hr, so the nurse converts the dose using the client's weight, the bag's concentration and 60 minutes per hour. The practice questions on this page are free, with no sign-up.
The same formula runs backward to check what dose a running pump is giving, which matters every time the drip is titrated or at handoff.
mcg/kg/min to mL/hr formula
- Concentration in mcg/mL
- mcg/mL = mg in bag × 1,000 ÷ mL in bag
- Dose to pump rate
- mL/hr = mcg/kg/min × kg × 60 ÷ mcg/mL
- Pump rate to dose
- mcg/kg/min = mL/hr × mcg/mL ÷ (kg × 60)
- Convert the mg in the bag to mcg before you divide. Mixing mg and mcg puts the answer off by a factor of 1,000.
- Don't forget the 60. The dose is per minute and the pump runs per hour.
- When you work back from a pump rate, round the dose to the nearest tenth. If it doesn't match the prescription, stop and verify before changing anything.
Worked example: mcg/kg/min to mL/hr
A client who weighs 78 kg is prescribed dopamine 5 mcg/kg/min IV. The premixed bag is dopamine 400 mg in 250 mL. At what rate will the nurse set the pump? Round to the nearest tenth.
- Concentration: 400 mg × 1,000 = 400,000 mcg, and 400,000 mcg ÷ 250 mL = 1,600 mcg/mL.
- Dose per minute: 5 mcg/kg/min × 78 kg = 390 mcg/min.
- Dose per hour: 390 mcg/min × 60 = 23,400 mcg/hr.
- Rate: 23,400 mcg/hr ÷ 1,600 mcg/mL = 14.625 mL/hr.
- Round: pump rates go to the nearest tenth, so 14.6 mL/hr.
Answer: 14.6 mL/hr
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Answer key
mcg/kg/min practice questions: answers and rationales
Try the questions first. Open one to read its answer and rationale.
Question 1A 64-year-old client in the intensive care unit is prescribed a dopamine infusion. The pharmacy supplies a premixed bag of dopamine 800 mg in 250 mL of dextrose 5% in water. What is the concentration of dopamine in the bag in mcg/mL? Round to the nearest whole number. Record your answer as a whole number.
Concentration in mcg/mL = mg in the bag × 1,000 ÷ mL in the bag. Convert first: 800 mg × 1,000 = 800,000 mcg. Then divide by the volume: 800,000 mcg ÷ 250 mL = 3,200 mcg/mL. Common errors: stopping at 800 ÷ 250 = 3.2, which is mg/mL and 1,000 times too small for a dose prescribed in mcg, or dividing 250 by 800. This is a concentrated bag; dopamine is also supplied as 1,600 mcg/mL, so the concentration printed on the bag is checked before the pump rate is calculated. Takeaway: change the mg in the bag to mcg before dividing by the mL, because the dose is prescribed in mcg/kg/min.
Sources: Open RN Nursing Skills (ACC adaptation), 5.17 Multi-Step Calculations; WisTech Open, Nursing Dosage Calculations: Introduction to mcg/kg/min; Open RN Nursing Skills (ACC adaptation), 5.4 Equivalencies; DailyMed: Dopamine Hydrochloride in 5% Dextrose Injection label (400 mg in 250 mL; dosing and titration); DailyMed: Dopamine Hydrochloride in Dextrose Injection label (800 mg in 250 mL = 3,200 mcg/mL)
Question 2A 71-year-old client in the cardiac care unit weighs 64 kg and is prescribed dobutamine 5 mcg/kg/min by continuous IV infusion. The premixed bag contains dobutamine 500 mg in 250 mL. At what rate, in mL/hr, will the nurse set the infusion pump? Round to the nearest tenth. Record your answer using 1 decimal place.
Concentration: 500 mg × 1,000 = 500,000 mcg, and 500,000 mcg ÷ 250 mL = 2,000 mcg/mL. Dose per minute: 5 mcg/kg/min × 64 kg = 320 mcg/min. Dose per hour: 320 mcg/min × 60 min/hr = 19,200 mcg/hr. Rate: 19,200 mcg/hr ÷ 2,000 mcg/mL = 9.6 mL/hr. In one line: 5 × 64 × 60 ÷ 2,000 = 9.6. Common errors: leaving out the 60, which gives 0.16 mL/hr, or leaving the bag in mg, which gives 9,600 mL/hr. An answer that far from a usual pump rate is a signal to recheck the units. Takeaway: mL/hr = mcg/kg/min × kg × 60 ÷ mcg/mL.
Sources: Open RN Nursing Skills (ACC adaptation), 5.17 Multi-Step Calculations; WisTech Open, Nursing Dosage Calculations: Introduction to mcg/kg/min; StatPearls: Dose Calculation Dimensional Analysis Factor-Label Method; DailyMed: Dobutamine in 5% Dextrose Injection label (500 mg and 1,000 mg in 250 mL; usual 2 to 20 mcg/kg/min)
Question 3A 56-year-old client in the intensive care unit weighs 72 kg and is receiving nitroprusside 50 mg in 250 mL of dextrose 5% in water by continuous IV infusion. During handoff, the oncoming nurse sees that the infusion pump is running at 32 mL/hr. What dose, in mcg/kg/min, is the client receiving? Round to the nearest tenth. Record your answer using 1 decimal place.
Work backward from the pump. Concentration: 50 mg × 1,000 = 50,000 mcg, and 50,000 mcg ÷ 250 mL = 200 mcg/mL. Dose per hour: 32 mL/hr × 200 mcg/mL = 6,400 mcg/hr. Dose per minute: 6,400 ÷ 60 = 106.67 mcg/min. Dose per kg: 106.67 mcg/min ÷ 72 kg = 1.48 mcg/kg/min, rounded to 1.5 mcg/kg/min. Common errors: forgetting to divide by 60 (88.9) or by the weight (106.7). The nurse compares the result with the prescribed dose; if they differ, the nurse verifies the prescription before changing the pump. Takeaway: mcg/kg/min = mL/hr × mcg/mL ÷ (kg × 60).
Sources: Open RN Nursing Skills (ACC adaptation), 5.17 Multi-Step Calculations; WisTech Open, Nursing Dosage Calculations: Introduction to mcg/kg/min; StatPearls: Dose Calculation Dimensional Analysis Factor-Label Method; DailyMed: Sodium Nitroprusside Injection label (50 mg in 250 mL = 200 mcg/mL; 0.3 to 10 mcg/kg/min)
Question 4The nurse titrates the dopamine infusion at 1415 as prescribed. At what rate, in mL/hr, will the nurse set the infusion pump? Round to the nearest tenth. Record your answer using 1 decimal place.
At 1415 the systolic BP is 84 mm Hg, still below 90 mm Hg, so the prescription calls for an increase of 5 mcg/kg/min: 5 + 5 = 10 mcg/kg/min, which is under the maximum of 20. Concentration: 400 mg × 1,000 ÷ 250 mL = 1,600 mcg/mL. Dose per minute: 10 mcg/kg/min × 79 kg = 790 mcg/min. Dose per hour: 790 × 60 = 47,400 mcg/hr. Rate: 47,400 mcg/hr ÷ 1,600 mcg/mL = 29.625 mL/hr, rounded to 29.6 mL/hr. Common errors: calculating the rate for 5 mcg/kg/min (14.8 mL/hr, the current rate), or leaving the pump unchanged because the BP has risen. Takeaway: find the new dose from the titration order first, then convert it to mL/hr.
Sources: Open RN Nursing Skills (ACC adaptation), 5.17 Multi-Step Calculations; WisTech Open, Nursing Dosage Calculations: Introduction to mcg/kg/min; StatPearls: Dose Calculation Dimensional Analysis Factor-Label Method; DailyMed: Dopamine Hydrochloride in 5% Dextrose Injection label (400 mg in 250 mL; dosing and titration)
Question 5A 62-year-old client in the cardiac intensive care unit weighs 203 lb and is receiving dobutamine at 5 mcg/kg/min. The premixed bag contains dobutamine 1,000 mg in 250 mL. The primary health care provider prescribes an increase to 7.5 mcg/kg/min. At what rate, in mL/hr, will the nurse set the infusion pump? Round the weight to the nearest tenth of a kilogram and the rate to the nearest tenth. Record your answer using 1 decimal place.
Weight: 203 lb ÷ 2.2 = 92.27 kg, rounded to 92.3 kg before use. Concentration: 1,000 mg × 1,000 ÷ 250 mL = 4,000 mcg/mL. The new dose replaces the old one; it is not added to it. Dose per minute: 7.5 mcg/kg/min × 92.3 kg = 692.25 mcg/min. Dose per hour: 692.25 × 60 = 41,535 mcg/hr. Rate: 41,535 mcg/hr ÷ 4,000 mcg/mL = 10.38 mL/hr, rounded to 10.4 mL/hr. Common errors: using 203 as kg (22.8 mL/hr), adding the doses to get 12.5 mcg/kg/min (17.3 mL/hr), or keeping the 5 mcg/kg/min rate of 6.9 mL/hr. Takeaway: convert lb to kg, then mL/hr = mcg/kg/min × kg × 60 ÷ mcg/mL, using only the dose now prescribed.
Sources: Open RN Nursing Skills (ACC adaptation), 5.17 Multi-Step Calculations; WisTech Open, Nursing Dosage Calculations: Introduction to mcg/kg/min; Open RN Nursing Skills (ACC adaptation), 5.4 Equivalencies; Open RN Nursing Skills (ACC adaptation), 5.5 Rounding; DailyMed: Dobutamine in 5% Dextrose Injection label (500 mg and 1,000 mg in 250 mL; usual 2 to 20 mcg/kg/min)
FAQ
mcg/kg/min calculation: FAQ
How do I convert mcg/kg/min to mL/hr?
How to calculate dopamine in mcg/kg/min?
How to convert from mcg/min to mcg/kg/min?
Sources: Open RN Nursing Skills (ACC adaptation), 5.17 Multi-Step Calculations; DailyMed: Dopamine Hydrochloride in 5% Dextrose Injection label; StatPearls: Dose Calculation Dimensional Analysis Factor-Label Method