Calcium Metabolism Part 1: Signs and Symptoms of Hypercalcemia

Hi, Dr. Raj here, and today we're gonna be talking about calcium metabolism, and I have fully enjoyed being part of your endocrinology journey, as well as just kind of leading the, the bus in regards to internal medicine board review and to get you the best score on your exams.

But today, let's focus on calcium.

Let's talk about hypercalcemia.

Let's talk about hypocalcemia.

Then we'll make some stops in Paget's disease of the bone.

We'll talk about osteoporosis.

But you know me.

Before we go take in the deep dive, we have to talk about some basics.

And I think one of the most important things is always about what are the forms of calcium, which kind of leads us into calcium physiology and what hormones are gonna be involved when we talk about regulating that perfect amount of calcium in the serum.

So if you were to order labs, and basically we call that a basic metabolic panel, a BMP, you're gonna get a calcium.

And when you look at that value by itself, what is the magic numbers? Somewhere between, like, eight and 10, okay? But what form of calcium is that number between eight and 10? That's what I wanna talk about today.

So when I take that step back, I'm gonna say 99% of all calcium is located where, everyone? It's located in the bone.

Only 1% is located in the serum, but go figure, what is gonna be the most highly tested thing, the most practical thing for my patients is that 1% that's in the serum, okay? Especially when we're talking about hyper and hypocalcemia.

So let's talk about those three forms in the serum itself.

Number one, calcium is gonna be bound to protein, and around 40 to 45% is bound to protein.

And of course, what is the most abundant protein in the serum? You got it, albumin.

And why are we gonna remember that? Because any time you tell me, "This is gonna be my serum calcium," my follow-up question will always be, "Well, what is the serum albumin?" Why? Because we always correct the calcium for the albumin.

And of course, if the albumin gets lower and lower and lower, there are some memorized correction factors to adjust for the calcium, and low albumin means that the calcium is also gonna be falsely low.

And we'll talk about these equations, but I'll give you a quick spoiler alert.

For every one of albumin below its normal value of four, we're gonna add around .8 to the serum calcium, and you could kind of rewind this video 1,000 times and hear that.

But also be careful because if your protein is too high, you also may consider that maybe your calcium in the serum is falsely elevated because you have too much protein.

So it kind of works both ways.

But three forms of calcium in the serum.

Number one, bound to protein.

What's the most abundant protein? Albumin.