Thread by @rabihmgeha

Teaching Rounds Day 4/15

Fever.

The Journey to a Diagnosis...

Part 1

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Let's zoom out.

The core problem we are often solving isn't fever.

It's "inflammation".

Fever is one of the most specific signs of inflammation,
but it's NOT sensitive enough to rely on every time.

Here is a striking example - bit.ly/396j6wf

Up to 50% of patients with Staph Aureus bacteremia had no fever!

It's not uncommon for us to count on other paths in to the world of inflammation.

The problem?

These back roads aren't as specific for inflammation.

But, again, we'd miss a lot of bad causes of inflammation if we relied on fever alone.

A fever is fairly specific for inflammation.
But it's not perfect...

Fever = elevation of the hypothalamic body temperature set point by inflammatory cytokines.

An elevated body temperature can also occur despite a normal hypothalamic set point...

This is what we call hyperthermia, which results from either:

1. Excess heat exposure - e.g, heat shock
2. Excess heat production - e.g, tonic muscle contraction
3. Impaired heat dissipation - e.g, anticholinergic toxicity

To summarize:

1. Fever is a specific clue to "inflammation"
But it's not sensitive enough.

Don't discount the presence of inflammation in an afebrile patient.

2. Most, but not all, elevated temperatures, represent a fever.

Consider hyperthermia early.
It could be life saving.

What causes a fever?

How can we organize this overwhelming list into a systematic approach?

Join us tomorrow for part 2 of this journey, where we plot our path.