Ouch that hurttts — Transcript

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1. 0:00so we have a 22 year old male he has a
2. 0:02seven year history of calcium oxalate
3. 0:04urolithiasis
4. 0:05urolithiasis is just a broad umbrella
5. 0:08term for
6. 0:09uh nephrolithiasis which is kidney
7. 0:11stones and ureteral lithius
8. 0:13eurotaro stones in addition to
9. 0:15consumption of water
10. 0:17a pharmacologic agent is recommended to
11. 0:19decrease recurrence of the stones what's
12. 0:21the moa
13. 0:22the starting point is just knowing the
14. 0:25factoid for the medical licensing exam
15. 0:27that
16. 0:28thiazide diuretics such as hctz they are
17. 0:31the drug
18. 0:32uh commonly prescribed to decrease
19. 0:34occurrence of calcium stones
20. 0:36okay so what's the moa thiazides
21. 0:40uh it they will inhibit a sodium
22. 0:44chloride symporter
23. 0:46on the apical membrane of the early
24. 0:49distal convoluted tubule okay
25. 0:51so prevent the reabsorption of sodium
26. 0:53chloride going the same direction
27. 0:54through that optical membrane applicable
28. 0:56means on the side of the urine
29. 0:58uh basolateral is on the side of the
30. 1:00blood so they inhibit a transporter
31. 1:02on the apical membrane of the early dct
32. 1:04sodium chloride symporter
33. 1:06we don't see that as an answer choice
34. 1:08here okay so you're probably like what
35. 1:09the [ __ ]
36. 1:10so we have to examine these answer
37. 1:12choices as to which one could relate to
38. 1:14thiazides okay
39. 1:16now how do thiazides relate to
40. 1:20calcium you need to know that they
41. 1:22promote the reabsorption of calcium
42. 1:25in the early dct okay that's what they
43. 1:28do
44. 1:28so you can make an argument say but yeah
45. 1:32that's not like the
46. 1:33moa per se of thiazides is it like
47. 1:36that's just an
48. 1:37indirect uh consequence
49. 1:40of giving it thiazide that's not the moa
50. 1:43i
51. 1:43could arguably agree with that however
52. 1:47uh this is on the nbme for step one so
53. 1:49this isn't
54. 1:50my opinion as to whether i i like this
55. 1:52or not um
56. 1:55this is asked on the envy of me for step
57. 1:56one where you get this type of question
58. 1:59and then the answer is that it promotes
59. 2:00calcium reabsorption
60. 2:02in the early just a convoluted tubule
61. 2:03okay this is what thiazides do uh
62. 2:08the answer choice that's not correct
63. 2:10promotes calcium reabsorption in the
64. 2:11late distilled conduit
65. 2:12tubule uh that would refer to uh
66. 2:15parathyroid hormone okay so uh
67. 2:18parathyroid hormone activates
68. 2:20a calcium channel on the optical
69. 2:24membrane
70. 2:24in the late dct so that could be the
71. 2:27answer if we had a parathyroid hormone
72. 2:29related question
73. 2:31looking at choice a decreases calcium
74. 2:34absorption in the small bowel
75. 2:35just wrong calcium absorption small
76. 2:38bowel is mediated by
77. 2:39125 dihydroxy vitamin d3 the active form
78. 2:42of d3
79. 2:44of course you have pth that will
80. 2:47activate one alpha hydroxylase the pct
81. 2:50of the kidney
82. 2:51and converting 25 to 125 and then that
83. 2:53promotes the calcium absorption small
84. 2:55bowel
85. 2:55doesn't relate to thiazides okay
86. 2:59um it should actually be noted this is
87. 3:02an interest this is an interesting
88. 3:03factoid piece of slash piece of value
89. 3:05for you as well
90. 3:06if they ask about dietary habits and
91. 3:08patients who have calcium stones
92. 3:10do not decrease calcium intake
93. 3:13okay that's really important you say but
94. 3:16how does that make sense like you
95. 3:17decrease calcium intake
96. 3:18why wouldn't that decrease your risk of
97. 3:20calcium stones
98. 3:21it's because it's the oxalate absorption
99. 3:25from the small bowel
100. 3:26that actually is most significant in
101. 3:28terms of uh
102. 3:30promoting stone development so
103. 3:33calcium will bind to oxalate in the
104. 3:35lumen of the small bowel
105. 3:38if you decrease calcium intake
106. 3:41then there's less oxalate or i should
107. 3:43say there's less calcium binding to
108. 3:45oxalate
109. 3:46therefore there's more oxalate available
110. 3:49to be
111. 3:50absorbed through the small bowel wall
112. 3:52okay so
113. 3:54do not decrease calcium intake that's an
114. 3:56important piece of value for you
115. 3:58looking at choice b decreases phosphate
116. 4:00concentration
117. 4:01in the distal convoluted tubule that
118. 4:03just doesn't have any relation here
119. 4:05uh whatsoever okay i just put that in as
120. 4:09a distractor
121. 4:10uh phosphate in relation to the kidney
122. 4:12pc
123. 4:13uh sorry uh pth pyrothyroid hormone
124. 4:16will decrease phosphate reabsorption in
125. 4:20the pct
126. 4:21of the kidney okay uh that's how
127. 4:24phosphate could relate to the kidney but
128. 4:26nothing related to the dct
129. 4:28we already talked about thiazides they
130. 4:30promote calcium
131. 4:32reabsorption in the early dct u.s simile
132. 4:35really
133. 4:35likes this piece of information as far
134. 4:39as
135. 4:40thiazides causing hypocalciuria
136. 4:44okay and in turn can cause hypercalcemia
137. 4:47so
138. 4:47hypergluc the mnemonic gluc hyperglute
139. 4:52uh that refers to our adverse effects of
140. 4:54thiazides
141. 4:55so hyper g being glycemia hyperglycemia
142. 4:59l lipidemia u uracemia
143. 5:02diazides can cause gout and c calcimia
144. 5:04so thiazides
145. 5:05has hypercalcemia because they cause
146. 5:08hypocalciuria okay
147. 5:11choice promotes stone dissolution the
148. 5:13acidification
149. 5:14late dct once again i just was an
150. 5:16[ __ ] put in something a little bit
151. 5:18complicated because if you're not sure
152. 5:19of the answer then you choose something
153. 5:21weird um
154. 5:24calcium oxalate stones are actually
155. 5:27better dissolved with alkalinization of
156. 5:29the urine so you can give
157. 5:31hydrochlorothiazide with citrate
158. 5:34okay which is a weak base and that can
159. 5:37promote the dissolution of stones okay
160. 5:39weak alkalinization of the urine
161. 5:41calcium phosphate stones form at a
162. 5:43slightly higher ph
163. 5:45uh they can uh you could or you can
164. 5:47increase dissolution of those with
165. 5:49acidification urine
166. 5:50and struvite stones caused by urease
167. 5:52positive organisms
168. 5:54those are the ammonium magnesium
169. 5:55phosphate stones those large ramhorn
170. 5:57looking stones
171. 5:58those are also dissolved with
172. 6:00acidification
173. 6:02you have to do surgery on those but
174. 6:03acidification will help with calcium
175. 6:05phosphate stones and it's through white
176. 6:07stones
177. 6:07but alkalinization will help with
178. 6:10calcium oxalate stones so
179. 6:12that's what's happening here okay so
180. 6:15increased
181. 6:16early dct reabsorption of calcium
182. 6:19as an indirect mechanism of giving
183. 6:22thiazides
184. 6:23and of course our main mechanism of
185. 6:25action of thiazides is inhibiting the
186. 6:27sodium chloride symporter in the early
187. 6:29dct
188. 6:30uh not a hard question okay like it's
189. 6:33all relative
190. 6:34i mean if you're close to sitting the
191. 6:36medical licensing exam
192. 6:37you're studying for step two this type
193. 6:38of question is actually like quote
194. 6:40unquote too
195. 6:41easy you're like come on michael like
196. 6:43give me something more difficult here
197. 6:44uh but i mean if you're like if you're
198. 6:47very much in the heart of your step one
199. 6:49prep you know
200. 6:50then this is a solid question and it's
201. 6:52on as i said it's on the nvmes for step
202. 6:54one
203. 6:54okay that's it