HY USMLE Q #1647 – Renal — Transcript

Full transcript

1. 0:00How's it going, guys? Past little
2. 0:01question for renal, 53-year-old dude,
3. 0:03TKA ecchymosis on his forearms, mild
4. 0:05bilateral pedal edema. And then we have
5. 0:07a renal biopsy, which I'll talk about as
6. 0:09we move through on choice A.
7. 0:11What's most likely to be seen in this
8. 0:12patient? What the [ __ ] am I saying?
9. 0:14What's most likely to be seen in this
10. 0:15patient, choice A?
11. 0:17BUN to creatinine ratio of 22 is wrong,
12. 0:19so BUN to creatinine ratio greater than
13. 0:2220 means pre-renal azotemia, which
14. 0:25doesn't relate to this image here.
15. 0:27Pre-renal azotemia would be something
16. 0:29causing decreased renal blood flow, like
17. 0:32chronic NSAID use,
18. 0:34diuretic use, chronic heart failure, can
19. 0:38be dehydration, uh vomiting, diarrhea
20. 0:41over many days. But when you have
21. 0:43decreased renal blood flow, the PCT is
22. 0:45going to try to reabsorb fluid to
23. 0:47compensate, and it accomplishes that by
24. 0:50increasing sodium and urea retention. So
25. 0:55by pulling those out of the urine, water
26. 0:57follows, so blood urea
27. 1:00nitrogen goes up,
28. 1:02and fractional excretion of sodium in
29. 1:04the urine goes down under 1% since
30. 1:06you're pulling it out of the urine. It's
31. 1:07pre-renal azotemia. Can do a lengthy
32. 1:10seminar on it, but we've got a renal
33. 1:12problem here. If anything, this would be
34. 1:14intrarenal, not pre-renal. Wrong [ __ ]
35. 1:17answer.
36. 1:21Choice B,
37. 1:221+ blood urine dipstick, negative RBCs
38. 1:25high powered field is wrong. This is
39. 1:26going to be rhabdomyolysis.
40. 1:28Now, if you've gone through my renal
41. 1:30playlist, you'll know I've said that
42. 1:31three to four RBCs per high powered
43. 1:34field is also considered negative. I've
44. 1:36made clips on it.
45. 1:37Okay, it shows up on one of the surgery
46. 1:39forms for 2CK, but you guys studying for
47. 1:41Step 1, it's the same deal. You just
48. 1:43need to know that zero to four RBCs per
49. 1:46high powered field is negative.
50. 1:48Rhabdomyolysis,
51. 1:50when you have muscle breakdown, you
52. 1:51release myoglobin into the blood,
53. 1:53and the urine dipstick cannot
54. 1:56differentiate
55. 1:58free myoglobin
56. 2:00from the hemoglobin that's in RBCs. So,
57. 2:04it registers blood on the dipstick,
58. 2:07but
59. 2:08when you do microscopy, light
60. 2:10microscopy, it's negative for RBCs when
61. 2:12you have rhabdo. So, it's picking up the
62. 2:14myoglobin. It's called false positive on
63. 2:17a false positive blood on your urine
64. 2:19dipstick.
65. 2:21Wrong [ __ ] answer.
66. 2:25Choice C. And it should just be noted
67. 2:27alcoholism big cause of rhabdomyolysis.
68. 2:30And they like giving this to you where a
69. 2:33patient can have acute tubular necrosis.
70. 2:35So, if you're forced to choose the renal
71. 2:36diagnosis the setting of rhabdo, it's
72. 2:39ATN. Choice C.
73. 2:411+ blood urine dipstick positive RBCs
74. 2:44high powered field. So, it's not an
75. 2:46exact number you have to memorize. Could
76. 2:48be 10, could be 20, 50.
77. 2:50I just told you that 0 to 4 is negative.
78. 2:52So, we clearly have positivity here.
79. 2:54This could be any nephritic syndrome.
80. 2:58This is a nephritic syndrome this
81. 2:59diagnosis. We look at this image which
82. 3:01as I said I'll explain I'm just being an
83. 3:03[ __ ] not revealing it right away, but
84. 3:06if you have let's say post-streptococcal
85. 3:07glomerulonephritis,
86. 3:09any of the vasculitides like Wegener,
87. 3:13Churg-Strauss, microscopic polyangiitis,
88. 3:15Goodpasture,
89. 3:16Alport syndrome, mutation type 4
90. 3:18collagen, IgA nephropathy. Okay, so when
91. 3:21we talk about nephritic syndromes, you
92. 3:24got to see a little bit of blood in the
93. 3:25urine.
94. 3:27Wrong [ __ ] answer.
95. 3:30Choice D insulin resistance correct
96. 3:31answer. Very
97. 3:33easy.
98. 3:34You're looking at Kimmelstiel-Wilson
99. 3:35nodules. It's pass level.
100. 3:37So, you see this image, you just say,
101. 3:39"Okay, well
102. 3:40we're looking at the pink These look
103. 3:42like pink circles, don't they?"
104. 3:44So, these are hyaline accumulations
105. 3:46Kimmelstiel-Wilson nodules. This is
106. 3:48diabetic glomerulosclerosis.
107. 3:51And in type 2 diabetes, insulin
108. 3:53resistance is the mechanism for that.
109. 3:56And you're not going to have blood in
110. 3:58the urine because it's nephrotic
111. 3:59syndrome.
112. 4:00So, you have to know which conditions
113. 4:02have blood in urine, which conditions
114. 4:03don't. So, I told you that in nephritic
115. 4:05syndromes a moment ago.
116. 4:06Nephrotic syndromes, membranous
117. 4:08glomerulonephropathy.
118. 4:10And you have
119. 4:11uh renal amyloidosis, multiple myeloma,
120. 4:13you've got diabetic glomerulosclerosis
121. 4:16as you have here, focal segmental
122. 4:18glomerulosclerosis, minimal change
123. 4:20disease. So, these are highly nephrotic
124. 4:21syndromes.
125. 4:22So, some of you say, "Wait, what's going
126. 4:25on with the
127. 4:26uh PT/INR, ecchymoses? Can you explain
128. 4:28that?" Okay, I'll get there in a second.
129. 4:31Relax, all right? So, the the mild
130. 4:34bilateral pedal edema, obviously that's
131. 4:35from the nephrotic syndrome, decreased
132. 4:37intravascular oncotic pressure cuz
133. 4:39you're losing the albumin in the urine.
134. 4:41So, you're just going to have
135. 4:42extravasation, transudation into the
136. 4:44interstitia. Now, choice C, wrong
137. 4:46[ __ ] answer, normal platelet count
138. 4:48150 to 450,000 per microliter. So,
139. 4:51obviously this is thrombocytopenia.
140. 4:53You need to know that in renal failure
141. 4:55you can get something called uremic
142. 4:57platelet dysfunction.
143. 5:00Okay? I make clips on it, go through my
144. 5:01YouTube. So, high BUN in the setting of
145. 5:05renal failure can cause a qualitative
146. 5:08dysfunction of platelets.
147. 5:10It's not a quantitative issue, it's a
148. 5:12qualitative issue.
149. 5:14So, BUN causes platelets to malfunction.
150. 5:18And you're going to have an increased
151. 5:20bleeding time, up arrow bleeding time,
152. 5:23but normal platelet count. Holy [ __ ]
153. 5:25It's the first time you're hearing it,
154. 5:27sounds weird, okay? Cuz if you get it as
155. 5:28an arrow question, you see something
156. 5:30like this, you'd be like, "Oh, like, you
157. 5:32know, increased bleeding time and then
158. 5:34decreased platelets." Wrong [ __ ]
159. 5:36answer, okay? It's increased bleeding
160. 5:38time, no change platelets. You're like,
161. 5:39"Wait, why?"
162. 5:41And you learn, okay, it's called uremic
163. 5:42platelet dysfunction. It's a qualitative
164. 5:44problem with platelets. Platelet count's
165. 5:46not low, and you can that in renal
166. 5:47failure.
167. 5:48It's another reason why patients who
168. 5:50have uh uremia,
169. 5:52which is the the word that means renal
170. 5:54failure,
171. 5:55why patients who have uremia need
172. 5:57dialysis if they're going into surgery
173. 5:58in particular because they'll get
174. 6:00excessive bleeding cuz their platelets
175. 6:02aren't working properly.
176. 6:04So,
177. 6:05thrombocytopenia,
178. 6:08wrong [ __ ] answer.