Nephrolithiasis (Kidney Stones): Role of Calcium

00:00 We’ll begin by looking at different types of nephrolithiasis or in other words, calcium stones being the most common, is that clear? So once again, calcium stones will be by far the most common and then with calcium stones, we will then divide this into two different subtypes but of all the kidney stones that we’ll take a look at, calcium stones, uric acid stones, cystine stones, your struvite stones, calcium by far is the most common.

00:29 Now, in the table that we see here and the ones that are to come, we shall then divide this into content of this stone.

00:38 Well, how exactly, what is precipitating? What this may then look like on your x-ray which is incredibly important, CT becomes important urine type of crystals if present and then a few comments.

00:51 Calcium’s where we are.

00:52 Your focus is calcium oxalate.

00:55 Also keep in mind that there is hypocitraturia.

01:00 Hypo, we’re in the urine, take a look at the suffix.

01:04 On x-ray if you were to take a look at a calcium stone, you can predict.

01:08 Well, most times when you find calcium nodule, let’s say that it was up in the lung or wherever it may be or if it’s calcium in the pancreas, you can expect it to be radiopaque.

01:19 And so that should be of no surprise.

01:21 On a CT, you find it to be radiopaque as well.

01:24 Now, there are different patterns here and the patterns are important.

01:27 The patterns that you’d find with calcium oxalate specifically would either be a dumbbell or what you’re seeing down here is going to be something like an envelope.

01:39 calcium oxalate.

01:40 The most common stone it is hypocitraturia is associated with decreased urinary pH, that’s important for you to pay attention to, results from ethylene glycol which is - take a look at the number of E’s, the letter E’s that you have in ethylene.

01:58 Conveniently, there are three.

02:00 There are conveniently three E’s in the word freeze, use that to your advantage please.

02:05 So antifreeze, what does that mean? The individual was well, during the summertime, adolescence tend to consume things that are rather peculiar.

02:14 Antifreeze, I guess it looks cool, and so they consume it and so therefore, may result in calcium oxalate but understand though, this could just be a genetic issue. Is that clear? Some people just have a predisposition to develop such stones.

02:29 Also, vitamin C abuse seems to be somehow associated with development of calcium oxalate.

02:36 If I were you, I would know that as being part of a clinical manifestation.

02:40 Now, whatever you wanna tell your patients in your clinical practice, you may do so but please note in medicine, that is important for us to take with us or hold on to.

02:50 What is the other type? Oh, we have the calcium phosphate.

02:54 Whenever we hear about phosphate, you should be thinking about your pH becoming alkaline.

02:58 Alkaline, whereas if it’s calcium oxalate, because of hypocitraturia, it is decreased urinary pH.

03:07 That is a huge point to distinguish between the two subtypes of calcium stones.

03:12 Here, the rest of it, pretty much the same, radiopaque, radiopaque imaging study, let it be CT or x-ray and the crystal here is wedge-shaped.

03:21 Now, here, what are the type of treatment modes that you wanna keep in mind? Interesting enough, here’s a diuretic.

03:29 So here’s calcium stones that you have but why would a diuretic come in handy here? It’s not that the diuretic is being used to try to flush out the stone, is that clear? Once again, listen, you’re not using the diuretics, specifically, thiazide here to flush out the stone.

03:43 You were specifically using your thiazide because think about where it works.

03:47 Your thiazide sensitive receptors on the distal convoluted tubule responsible for normally well, it inhibits a certain chloride channel, correct? Sodium chloride channel and behaves like a diuretic.

04:01 That’s not what you’re going for here.

04:03 You have too much calcium in the urine, so what do you think this thiazide does? Yes, it actually removes the calcium.

04:10 So if you’re familiar with it, fantastic, if you weren’t, get familiar with it real quick.

04:15 Thiazides remove calcium from the urine.

04:18 Now, very rarely clinically would you find a patient who’s taken a thiazide that results in hypercalcemia.

04:25 I can tell you that clinically.

04:26 However, if you do have a patient that concomitantly also has a PTH problem, something like a primary hyperparathyroidism, obviously, that’s going to exacerbate the issue, is that clear? Next, low sodium, and here’s citrate as well.

04:40 Those things that you wanna keep in mind when dealing with calcium stones.

04:43 Think about hypercitraturia, this is something that for the most about the citrate but then obviously be more in your plasma.

04:51 So look for treatment here being thiazides, low sodium, and citrate.