Historically, serum creatinine was analyzed from a blood sample using a method called alkaline picrate. In addition to creatinine molecules, though, it also “counted” non-creatinine molecules that falsely elevated the resulting value by as much as 20%. This assay method was used for decades in the development of creatinine clearance estimates, such as the Cockcroft-Gault method.
Within the past 10-15 year, however, laboratories have largely moved to a new assay called IDMS (isotope dilution mass spectrometry). This method does not detect the non-creatinine molecules, which means that the IDMS value is often 10-20% lower than the more conventional assay. Because older equations, like Cockcroft-Gault, were created and validated using a non-IDMS assay, this poses a problem for estimating creatinine clearance (a surrogate for glomerular filtration rate) when using an IDMS-based lab assay.
Converting from IDMS to non-IDMS (Conventional)
In the United States, vitamin D supplementation is primarily available as vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Although these two have historically been considered interchangeable and equipotent, the current body of literature strongly supports the preference of Vitamin D3 (cholecalciferol) over D2 (ergocalciferol).
Vitamin D2 versus Vitamin D3
Vitamin D3 (cholecalciferol) is produced by the human body in response to sunlight and is also available through dietary sources, such as fish. In contrast, vitamin D2 (ergocalciferol) is not produced in the human body, but is created by exposing certain plant-derived materials to ultraviolet light.
Magnesium repletion is very common in hospitalized patients. Is there any difference between PO and IV magnesium in patients without symptoms of hypomagnesemia?
Ciprofloxacin binds to divalent and trivalent cations (calcium, magnesium, etc). Are there any recommendations regarding giving crushed ciprofloxacin via an enteral feeding tube, such as holding nutrition or increasing the dose?
Is there a preferred agent for VTE prophylaxis in trauma patients? Is there a superior dosing strategy for these high-risk patients?
The selection and dosing of pharmacologic VTE prophylaxis in trauma patients has a troubled, controversial past. The literature surrounding the topic is riddled with small, conflicting trials and methodological flaws.
How should aspiration pneumonia be treated? Is anaerobic coverage required?
The concept of aspiration pneumonia and anaerobic coverage is a complex, controversial topic. Like most controversial topics, there is paucity of evidence, and the literature that does exist is controversial.
Is there a maximum insulin glargine (Lantus) single-injection dose? Anecdotally, I have heard that patients receiving more than 50 units should split the dose from daily dosing to twice-daily. What’s the evidence?
The question of a maximum insulin glargine dose is not straightforward because it encompasses several issues: Continue reading