PSPal Surgery

Clinical calculators

The numbers you are asked for on a ward round, worked out in the browser. Free, instant, nothing to install and no sign-up.

Written and clinically reviewed by , consultant minimally invasive and bariatric surgeon, Al-Makassed Hospital, Jerusalem, and Assistant Professor of Surgery, Al-Quds University. Last updated .

New · Fluids · 6 calculators in one IV fluids calculator Adult maintenance and the bag to prescribe, the 4-2-1 rule for children, Parkland for burns, drip rates, sodium correction and the potassium deficit, from the Intravenous Fluids guide. Calcium · mg/dL or mmol/L Corrected calcium calculator A low albumin drops the reported calcium without touching the ionised fraction that actually matters. Enter the calcium and the albumin, in either set of units, and get the corrected value with what it means. Liver · ALT and ALP R-factor calculator Enter the ALT and ALP with your own upper limits of normal and see instantly whether a liver injury is hepatocellular, mixed or cholestatic — the first fork in the road of every abnormal liver panel.

What each one is for

CalculatorAnswersWhere you will need it
IV fluids What bag, how much, how fast? And how fast may this sodium move? Every surgical patient who is nil by mouth, burned, vomiting or hyponatraemic
Corrected calcium Is this calcium really abnormal, or is the albumin low? Any surgical inpatient, and every patient on day one after a thyroidectomy
R-factor Is this liver injury hepatocellular, mixed or cholestatic? The jaundiced patient, and any abnormal liver panel

A calculator is not a decision

Each of these turns a few numbers into an answer. Neither knows your patient, your laboratory's reference intervals, or the clinical picture in front of you. Read every result against the interval printed on your own report, and treat the patient rather than the number — the pages behind each calculator explain exactly where the arithmetic stops being reliable.

Where they come from

Each calculator sits beside the teaching that explains it. The corrected calcium page carries the formula in both unit systems, a worked example, the four ways a calcium result misleads you, and the point at which you should stop correcting and measure the ionised calcium instead. The R-factor page does the same for liver tests.

TopicCalcium & the parathyroid The circuit, the hypercalcaemic patient, and the parathyroid operation. Guide Reading liver function tests Three patterns, one table, and the three questions to ask of every set of results. PracticeClerk a patient Nine simulated surgical patients, with a scored debrief.

Coming to this page

  • Calcium–creatinine clearance ratio — the number that separates familial hypocalciuric hypercalcaemia from primary hyperparathyroidism
  • Anion gap and the arterial blood gas, alongside the Acid–Base guide
  • Body mass index and excess weight loss, for the bariatric clinic
Cover of Calcium & the Parathyroid

The calculators come out of the free books

The corrected calcium is Figure 11 of Calcium & the Parathyroid; the R-factor is from Bile and Jaundice; the IV fluids calculator is from Intravenous Fluids. Each is 31–35 illustrated pages, free to download, with a DOI.

Calcium & the Parathyroid Bile and Jaundice

Related pages

CalculatorCorrected calciumAlbumin changes the number, not the disease.CalculatorR-factorHepatocellular, mixed or cholestatic.PracticeClerk a patientNine surgical histories to take.SeriesAll the guidesWhat is published and what is coming.