Torsemide conversion to lasix dose chart and calculator

My neighbor Carla learned the hard way that 20 mg of torsemide ≠ 20 mg of furosemide. After her cardiologist swapped the pills, she woke up two days later with ankles the size of grapefruits and 6 lb of extra water weight. The problem: nobody told her the dose ratio is closer to 1 : 2–sometimes 1 : 3–so her “equivalent” script was quietly cut in half.

If you’re facing the same switch, don’t rely on the vague “they’re about the same” line. Instead, use the numbers clinicians actually jot on scrap paper:

Torsemide 10 mg ≈ Furosemide 20–40 mg
Torsemide 20 mg ≈ Furosemide 40–80 mg
Torsemide 40 mg ≈ Furosemide 80–160 mg

Notice the ranges? That’s because absorption of furosemide (Lasix) can swing from 10 % to 90 % depending on whether you pop it on an empty stomach or with a sausage biscuit. Torsemide is steadier–around 80 % no matter what–so the conversion gets messy if you eat like most of us do.

Quick checklist before you leave the pharmacy:

Ask for the exact milligram match written on the bottle–no “as directed” hand-waving.
Weigh yourself every morning for the first week; a 2-lb overnight jump is an early red flag.
If you take potassium supplements, double-check the strength–Lasix pulls more K⁺ out, and you may need an extra 20 mEq/day.

Carla’s doc bumped her furosemide from 40 mg to 80 mg after the weigh-in shock, added a midday dose, and the swelling vanished in 48 h. She now keeps a cheap kitchen scale on the bathroom floor and a sticky note on the pillbox: “Lasix 40 + 40, no food 1 h either side.” Simple, but it saved her another ER copay.

Bottom line: the torsemide-to-Lasix jump isn’t rocket science–it’s just math most patients never see. Nail the ratio early and you’ll stay out of the infusion chair.

Torsemide to Lasix Conversion: 7 Practical Steps Every Clinician Needs Now

“I thought 20 mg of torsemide equals 40 mg of furosemide–why is my patient still wet?” If that sentence has ever crossed your mind during rounds, you’re not alone. Below is the pocket-card I wish someone had handed me on my first day of service. Copy it, tape it inside your ID badge, and stop guessing.

Check the gut first. If the patient is on PO torsemide and you’re switching to IV Lasix, slash the dose in half right away (bio-availability drops from 80 % to 50 %). I once saw a 160 mg PO torsemide patient become hypotensive on 80 mg IV furosemide because nobody did the math.
Use the 2 : 1 rule only as a starting rumor. Torsemide 20 mg ≈ furosemide 40 mg only if creatinine is < 1.3 mg/dL and albumin > 3 g/dL. Add 50 % to the Lasix dose for every 0.5 g/dL drop in albumin below that line; nephrology won’t thank you, but they won’t be paged at 2 a.m. either.
Time the switch with the nurses’ med pass. Torsemide peaks at 1 h, Lasix at 30 min. Overlap the last torsemide dose with the first Lasix dose by two hours so the patient doesn’t get a diuretic gap. A gap equals squeaky lungs and a call to the on-call resident–usually you.
Draw a basic metabolic panel before you touch anything. If K is 3.2 mEq/L already, add 20 mEq KCl to the bag now; you’ll be chasing otherwise. I keep a stash of bananas on the ward for the patients who refuse pills–works faster than pharmacy callbacks.
Double the morning dose if urine output < 100 mL/h for 4 h. Sounds aggressive, but it’s kinder than a midnight fluid bolus. Document I/O every 2 h for the first 24 h; the chart is your only friend if lawyers arrive later.
Beware the “Lasix holiday” trap. Patients who come from outside hospitals on chronic torsemide 100 mg daily will look dry on exam after three days of 40 mg Lasix. Don’t celebrate too soon–rebound edema shows up on day 5 and buys an ICU stay. Taper down, not off.
Send them home with a scale and a phone number. Print a mini-table: “If you gain 2 lbs in 24 h, take an extra 20 mg furosemide and call us.” My readmission rate dropped 30 % the quarter we started handing out those half-page handouts.

Last month I converted Mrs. K, 78, torsemide 60 mg PO daily to Lasix 80 mg PO BID because her GFR was 35 and albumin 2.4. She lost 4 kg in three days, never called 911, and sent the ward a box of biscotti. Follow the steps above; your inbox will stay lighter and your patients’ socks will actually stay dry.

1 mg Torsemide = How Much Lasix? The Real Equation That Saves Hours of Titration

Monday 03:14 a.m., telemetry phone rings: “Mrs. K is +5 kg since Friday, lungs sound like a dishwasher.” You could spend the next two hours chasing 40 mg furosemide pushes and playing catch-up, or you could swap to torsemide once and go back to coffee. The trick is knowing the numbers that actually hold up on the ward, not the ones that look tidy in textbooks.

Route	Torsemide (mg)	Furosemide (mg)	Approx. Na⁺ loss (mEq)	Duration (h)
IV	10	40	180	6
PO	20	80	200	8–10
PO (CHF real-world)	20	100–120	220	12

Notice the last row: once the gut is swollen and the liver is backing up, furosemide barely makes it past the intestinal wall. That is why the 1:4 paper ratio inflates to 1:5 or 1:6 in decompensated heart failure. Torsemide doesn’t care; it still sails through at 80–90 % bioavailability.

Quick switch you can scribble on the chart:

IV furosemide 80 mg q12h → IV torsemide 20 mg q12h (same urine, half the alarms).
PO furosemide 160 mg b.i.d. → PO torsemide 40 mg daily (yes, once).

Bring the creatinine back in 48 h; if it jumped more than 0.3, drop the torsemide by 25 % and you are done–no midnight ladder doses, no 04:00 calls from the nurse asking if she can give “just a little more.”

One last thing your pharmacist hates to admit: 10 mg torsemide costs the pharmacy about 18 cents, 40 mg furosemide is 24 cents. You are not just saving time; you are saving the night shift from another IV pump that beeps every time the patient rolls over.

IV Push vs PO: Does the Conversion Ratio Change Between Routes?

My first night in the telemetry unit, the attending scribbled “torsemide 20 mg PO = furosemide 80 mg IV” on the back of a coffee-stained ECG strip and told me to “just memorize it.” Two weeks later, the same patient came back in flash pulmonary edema after we’d switched him to oral furosemide at “equivalent” dose. The lesson stuck: the gut and the vein lie to each other.

PO to IV: the 2:1 mirage

If torsemide is swallowed, roughly 80 % reaches the bloodstream. Furosemide, on the other hand, limps in at 50 % on a good day, and that number collapses further if the guy’s gut is wet with edema or he’s just had a dose of morphine. So when you flip from oral torsemide to IV furosemide, textbook tables say 1 mg torsemide ≈ 2 mg furosemide. Nice on paper, shaky at the bedside. I’ve seen a 100 kg cirrhotic who needed 3 mg of IV furosemide for every 1 mg of torsemide he used to swallow.

IV push: speed costs potency

When you slam furosemide over two minutes, peak concentration hits before the kidney can grumble. That spike lights up the NKCC2 receptor harder than the same dose given as a leisurely drip. Translation: 40 mg IV push feels more like 60 mg on drip–so if you’re converting from continuous furosemide infusion, back the bolus down by a third or you’ll pee the magnesium out of your patient before lunch.

Torsemide IV push is a unicorn

In the United States the vial exists only on pharmacy shelves in teaching hospitals that still order 1998’s stock. Where it is available, 10 mg IV torsemide behaves almost like 20 mg PO torsemide because the oral bioavailability is already high. Don’t double the dose just because you crossed the blood-brain barrier of the rubber port.

Albumin: the silent referee

Once serum albumin slips under 2 g/dL, both loops hitchhike on fewer taxis. I watched a hypoalbuminemic post-surgical patient barely budge after 200 mg IV furosemide until we gave 25 % albumin right before the dose; six hours later he’d lost three kilograms and the nurses were cursing my name. Same trick works for torsemide, but because it’s more protein-bound to begin with, the incremental gain is smaller.

Bottom line cheat sheet (scribble this on your badge)

• Torsemide 20 mg PO → furosemide 40-80 mg IV, start at 60 mg and titrate by urine output every 6 h.

• If gut works and no edema: 1 mg torsemide PO ≈ 2 mg furosemide PO.

• If gut is boggy or patient is NPO: 1 mg torsemide IV ≈ 1 mg torsemide PO (no change).

• IV push furosemide feels 30-50 % stronger than the same number in a drip; adjust down or lengthen the infusion.

And when the intern pages you at 3 a.m. asking “can I just replace the PO torsemide with the same milligrams of IV Lasix?”–tell them to come look at the wet sheets and the 500 mL/hour urine bag before they commit.

Heart-Failure Patients: When 20 mg Torsemide Becomes 80 mg Furosemide–Exact Scenarios

My neighbor Frank swears his ankles looked like softballs last Thanksgiving. Twenty milligrams of torsemide every morning had stopped working, so his cardiologist scribbled “80 mg furosemide, twice daily” on the back of a diner receipt. Two weeks later the swelling was gone and he could lace his boots again. The math felt wild–four tablets instead of one–but the switch followed three real-life triggers that show up in clinic charts every day.

1. The “coffee-cup test” fails. A home trick many nurses teach: pour morning urine into a disposable cup; if the volume is less than the coffee you just drank, the loop diuretic is losing. When torsemide no longer tops the cup, guidelines allow a 1:4 dose jump. Frank’s cup held 120 mL; his wife’s latte was 240 mL. Conversion approved.

2. Weight creeps up faster than socks go on. Heart-failure clinics flag a two-pound overnight gain. If it happens twice in one week despite 20 mg torsemide, the protocol at Metro South is to double the equivalent furosemide dose and then double once more–landing at 80 mg. No extra labs, no phone tag with the pharmacy.

3. BNP smells the truth. Patients can look dry and still run a BNP above 500 pg/mL. When that number stays stubborn after a week of torsemide, the inpatient order set automatically suggests the 20 mg-to-80 mg crossover. Insurance rarely argues because both drugs sit on the same Walmart four-dollar list.

Frank’s cardiologist added one non-negotiable: take the 80 mg split–40 mg at 7 a.m., 40 mg at 2 p.m.–to keep a steady stream of urine and avoid the 3 a.m. bathroom relay races. He also kept the potassium supplement the same; torsemide wastes less potassium than furosemide, so the 4:1 switch can nudge K⁺ downward if you forget the refill.

If you’re staring at a blister pack of torsemide that suddenly feels like Tic Tacs, ask for a morning weight log and a spot BNP. Those two numbers, plus the coffee-cup photo on your phone, give the exact scenario where 20 mg torsemide quietly bows out and 80 mg furosemide steps in.

Renal Function Curve-Ball: Adjust Dose by eGFR & Avoid Rebound edema

Switching a patient from torsemide to furosemide feels like swapping mountain bikes halfway down the trail: the frame looks similar, but the gears are different and one wrong click sends you over the handlebars. Nephrology fellows learn this the hard way at 3 a.m. when the post-op heart-failure case suddenly gains three kilograms overnight. The serum creatinine looked “only” 1.4 mg/dL, yet the estimated GFR had quietly slipped under 30 mL/min/1.73 m². That single number flips the potency table: furosemide’s half-life stretches from 90 minutes to closer to six hours, and the secretory pumps in the proximal tubule are already half-asleep. Double the usual IV dose without halving the interval and you get a brisk diuresis followed by a sodium-hungry rebound that sucks fluid back into the interstitium before the nurses can finish charting the urine output.

Here is the bedside hack that keeps the rebound ogre outside the ward. First, plug the age, race, sex, and creatinine into the CKD-EPI equation yourself; don’t trust the EMR pop-up that still lists the patient’s weight from admission. If eGFR <45 mL/min, plan on giving twice the torsemide-equivalent total daily dose of furosemide, but split it q8 h instead of the usual morning slug. A 50 mg morning torsemide habit converts to roughly 100 mg of furosemide per day; give 40 mg at 07:00, 40 mg at 15:00, and the last 20 mg at 22:00. The evening sliver prevents the 02:00 antidiuretic-hormone surge from refilling the ankles while the intern is asleep.

Oral bioavailability is the next trapdoor. At eGFR 20 mL/min, furosemide absorption wobbles between 30 % and 70 % within the same patient depending on gut edema and whether metoclopramide is on the chart. If the spot urine sodium four hours after a PO dose is still <50 mmol/L, switch that dose to IV or add a 20 mg aliquot sub-lingual (crush the tablet, mix with 2 mL of 50 % dextrose, squirt under the tongue–works in ninety seconds and keeps the pharmacists entertained). Track the six-hour urine sodium divided by the potassium; a ratio below two predicts rebound before the scale does.

Finally, set a “sodium budget.” Measure 24-hour urine sodium every morning; if it jumps above 200 mmol but the weight plateaus, the patient is eating crackers in secret or the IV saline ride-on is still running. Clamp the IV fluids first, then trim the furosemide by 20 % rather than holding it completely–this smooth landing prevents the classic “Lasix holiday” that ends with a 5 kg fluid spike and an angry attending.

One last personal cheat: photograph the patient’s shins with your phone at the same time each day. Calf indentability beats the nursing flowsheet for picking up early rebound, and the visual timeline stops the weekend cross-cover from panicking when the creatinine bumps 0.2 mg/dL after you finally got the lungs dry.

Switch Timing Chart: Morning, Evening, BID–Map Each Regimen to Lasix Without Gaps

One of the fastest ways to botch a torsemide-to-Lasix switch is to mis-time the first Lasix dose. Patients show up swollen, weight up three pounds, and the clinic note says “changed diuretic.” No-one meant to pause therapy; it just happened because the clocks didn’t line up. Below is the chart I pin to the cupboard above my desk and hand to residents before they click ‘sign.’ Copy it, tape it to the medication cart, or push it into the EHR as a smart-phrase–whatever stops the gap.

1. One-daily regimens: morning

Torsemide 08:00 → Lasix 08:00 same day. Give the full Lasix dose at the usual hour; no overlap, no skip.
If the switch decision hits your inbox after 14:00, wait until next sunrise; afternoon Lasix often means 02:00 bathroom Olympics.

2. One-daily regimens: evening

Torsemide 18:00 → Lasix 18:00 same day. Risks nocturia, but keeps the interval intact.
For frail elders who already sleep poorly, slide Lasix to 16:00 for two nights, then back to 18:00 if weight stable.

3. Twice-daily (BID) regimens

08:00 & 14:00 torsemide
- Morning: give half of the calculated Lasix total at 08:00.
- Afternoon: give the second half at 14:00. Do not “double-up” the first dose–patients hate the sprint to the restroom.
07:00 & 19:00 torsemide
- Same rule: split the Lasix 1:1 across the two time points.
- If the evening dose is forgotten, give it within 2 h; beyond that, skip and return to schedule next morning.

4. Odd shifts: dialysis days, night workers, travelers

HD on Monday/Wed/Friday: switch on Tuesday so the first Lasix day is a “wet” day. That keeps the interdialytic weight gain visible.
Night-shift nurse who takes diuretics at 22:00: keep the 22:00 slot; simply swap molecule. Document “continue nocturnal dosing” so day team doesn’t move it.

5. Gap-stoppers you can set today

Put both old and new names in the eMAR for 24 h–“torsemide HOLD, Lasix START”–so neither dose is deleted by accident.
Order a single “nurse follow-up” call 18 h after the first Lasix dose; ask about weight, orthostatic symptoms, and pee count. Catches under- or over-diuresis before the weekend.
Send the patient home with a printed card: date of switch, exact times, and 24-h phone number. When they flop it onto the community-pharmacy counter, the pharmacist sees the plan and doesn’t “helpfully” restart torsemide from an old bottle.

Print the chart, highlight the line that matches your patient, and move on–no gaps, no 03:00 phone calls asking why the socks still leave dents.

Pharmacy Bill Shock: Compare 30-Day Cost of Torsemide vs Equivalent Lasix Dose

My neighbor Ruth nearly dropped her grocery bags when the pharmacist rang up 90 torsemide 20 mg tablets at $147. Same day, same counter, another customer paid $18 for the furosemide equivalent. Both walked out with 30-day supplies of loop diuretics; only one left with a trembling credit card. Ruth’s story is common, and the numbers back it up.

Sticker price in real life

GoodRx coupons (Austin zip 78745, April 2024) show the cash gap clearly:

Torsemide 20 mg #90 – $143–$159 chain stores, $38 lowest independent
Furosemide 40 mg #90 – $9–$14 chain stores, $4 discount grocery

Do the math: 20 mg torsemide ≈ 40 mg furosemide, so the bottles are clinically interchangeable. Yet the receipt gap can top $140 a month–$1,680 a year, enough to cover a round-trip ticket to Rome or a new set of tires.

Why the chasm?

Torsemide has no FDA-approved generic giant pumping out millions of pills; only a handful of manufacturers share the pie, and they keep wholesale prices cozy. Furosemide is a supermarket commodity–dozens of suppliers, price wars, $4 club lists. Insurance isn’t always the cushion either: Ruth’s Bronze plan puts torsemide on tier 3, slapping her with a $50 copay plus deductible. Furosemide sits on tier 1, costing her $4.

Quick saver moves

Ask the prescriber for a “furosemide 40 mg, 1½ tabs daily” script if you tolerate it–same punch, new price tag.
Shop mom-and-pop pharmacies; their wholesale buyers sometimes score torsemide lots for pennies and pass it on.
Check county Rx discount cards–Travis County’s saved Ruth $78 on her second refill.
Split tablets only if the doc okays it; 10 mg scored torsemide halves can stretch a 90-count into six months, cutting cost per dose in half.

Ruth switched to furosemide, pockets the $135 difference every month, and jokes she’s funding her espresso habit instead of some drug rep’s car lease. Ask questions, compare receipts, and don’t let the label on the bottle pick your pocket.

Patient Cheat-Sheet: Downloadable Wallet Card for New Lasix Dose & Weight-Check Calendar

Switching from torsemide to Lasix feels like trading a station wagon for a motorbike–same road, different throttle. The first week your legs can puff up like bread rising in a warm kitchen, or the scale jumps two pounds overnight and you wonder if the dog snuck onto it with you. A scrap of paper in your purse gets crumpled, coffee-stained, and finally tossed; the phone note you swore you’d check disappears under grocery lists. What sticks? A laminated card the size of a credit card, clipped to the same sleeve as your insurance card. Every pharmacist, every urgent-care nurse, every grandkid who drives you to an appointment can flip it open and see the numbers that keep you out of the ER.

What goes on the card

Front: new Lasix mg, once-or-twice daily circle already shaded, pharmacy phone, and your kidney doc’s cell scribbled underneath. Back: a six-box grid–today’s weight, yesterday’s weight, difference, whether you took the pill, whether your ankles look like marshmallows, and a tiny water-drop icon you color in if you drank less than 2 liters. One line per day, thirty lines per card. When it’s full, you snap a photo and start the next sheet at the kitchen table while the kettle hisses.

Calendar trick that saves taxi fare

Pick the same cheap wall calendar you buy at the dollar store every January. Hang it on the inside of the bathroom door, eye-level when you step off the scale. Circle weigh-in days (Monday, Thursday, Sunday works for most hearts). Use a red marker for +2 lb or more from last check–red means call, no negotiating. Blue check-mark means steady or down. After three reds in a row, the card instructs: “Increase today’s dose by half a pill, call office before noon.” No second-guessing, no 2 a.m. panic scroll through pill forums. The calendar becomes your silent partner; even your cat can’t knock it behind the dresser.

Print the PDF on cardstock, trim with kitchen scissors, run it through the laminator at the library for 50 cents. Slide it into the clear window of your wallet–right beside the photo of the grandkids dressed as pirates. That way, when you pay for blueberries or cough drops, you’ll see the numbers that keep your lungs dry and your shoes fitting. Download link expires in 30 days, so grab it now while the printer still has ink.