Upload
misbah
View
219
Download
0
Embed Size (px)
Citation preview
7/26/2019 Approach to Diagnosis of Hypokalemia
1/44
Dr Chaitanya Vemuri
Approach to Diagnosis of
Hypokalemia
7/26/2019 Approach to Diagnosis of Hypokalemia
2/44
Most abundant cation in human body
Regulates intracellular enzyme function and helps to determine
neuromuscular & cardiovascular tissue excitability.
9 !of total body "# $ %ntracellular
predominantly in muscle '
( ! $ )xtracellular fluid
* ( ! $ +lasma
Introduction : Potassium
7/26/2019 Approach to Diagnosis of Hypokalemia
3/44
Ratioof extracellular "# to %ntracellular "# $ determines
the membrane potential
,he acuity of changesin serum potassium concentration& membrane potential determines clinical symptoms and
underlying signs
+lasma concentration varies from -. to ./ mmol0l
7/26/2019 Approach to Diagnosis of Hypokalemia
4/44
1igh intracellular concentration of "# is maintained by
several factors that govern "# upta2e & release from
intracellular compartment
"# upta2e into cells $ actively driven by 3a#"#4,+ase
5ea2bac2 into )C6 $ opposed by electrical gradient
Physiology Of PotassiumHomeostasis
7/26/2019 Approach to Diagnosis of Hypokalemia
5/44
7/26/2019 Approach to Diagnosis of Hypokalemia
6/44
4cid base status
+ancreatic hormones $ insulin 7 glucagon
Catecholamines
4ldosterone
+lasma 8smolality
)xercise
Cellular "# content
Factors modifying transcellular K+distribution
7/26/2019 Approach to Diagnosis of Hypokalemia
7/44
4l2alemiapromotes "# upta2e by cells
4cidemia diminishes "# upta2e by cells
4cute respiratory al2alosis7 incontrast increase plasma "#
by . mmol0l per .( p1 unit
d0t increased adrenergic activity
Acid ase !tatus
7/26/2019 Approach to Diagnosis of Hypokalemia
8/44
%nsulinstimulates cellular upta2e of "# by activating
3a#"#4,+ase decreasing plasma "# '
%nsulin affects "# transport independently of glucose
upta2e
:lucagon increase plasma "#independently of changes
in plasma glucose 0 insulin
Pancreatic Hormones
7/26/2019 Approach to Diagnosis of Hypokalemia
9/44
;eta adrenergic activity < hypo2alemia
4lpha adrenergic antagonists < hypo2alemia
"atecholamines
7/26/2019 Approach to Diagnosis of Hypokalemia
10/44
%nvitro studies4ldosterone stimulates 3a#"#4,+ase and thereby
activating 3a # influx
Aldosterone
7/26/2019 Approach to Diagnosis of Hypokalemia
11/44
1yperosmolality Mannitol infusion 0 hyperglycemia in
DM ' $ increase plasma "#
)ach ( m8sm 0 "g rise in plasma osmolality7 increases
plasma "# by ./ mmol0l
Osmolality
7/26/2019 Approach to Diagnosis of Hypokalemia
12/44
Recurrent contraction increases "# egress from muscle
Modest exercise $ high "# in )C6 in local environment
produces vasodilatation & thereby increased regional blood
flo=
>evere exercise $ increase plasma "# modestly
+hysical training increases 3a#"#4,+ase activity in s2eletal
muscle =hich helps s2eletal muscle to ta2e up "# again
#$ercise
7/26/2019 Approach to Diagnosis of Hypokalemia
13/44
%ntracellular "# affects intra to extracellular "#
?ith "# depletion 7
"# loss from )C6 @ %C6 losscausing increased "i # 0 "e#
"# depletion $ hyperpolarization
"# retention $ depolarization
"ellular K+ "ontent
7/26/2019 Approach to Diagnosis of Hypokalemia
14/44
"idney is dominant in sustaining "# balance
@9 ! "# $ excreted in urine
Remainder through feces
Decrease in :6R7 "# excretion via feces increased
:% 5oss $ "# secretion by proximal & distal colon
K+ alance
7/26/2019 Approach to Diagnosis of Hypokalemia
15/44
%enal Handling of K+:lomerulus$ freely filtered
+C,7 ,hic2 4s limb 581 $
reabsorbed
7/26/2019 Approach to Diagnosis of Hypokalemia
16/44
"ortical "ollecting Duct
7/26/2019 Approach to Diagnosis of Hypokalemia
17/44
Defined as plasma concentration of "# * -.A m)B05
Mild 1ypo2alemia $ -. < -.A m)B05 $ asymptomatic
1ypo2alemia * -. m)B05 $ symptomatic
Clinical manifestations of hypo2alemia vary greatly
bet=een individual patients&
their severitydepends on degree of hypo2alemia
Hypokalemia
7/26/2019 Approach to Diagnosis of Hypokalemia
18/44
Clinical features
%nvestigations
Diagnosis
7/26/2019 Approach to Diagnosis of Hypokalemia
19/44
Mild hypo2alemia $ generally asymptomatic
%ncreased ris2 of mortality for pts =ith cardiovascular disease < trigger ventricular
tachycardia 0 ventricular fibrillation
decrease "# $ d0t sympathetic stimulation'
Digitalis induced arrhythmias < can occur =ith normal drug levels if hypo2alemia is
present
Diuretic induced hypo2alemia & hypomagnesemia must be avoided in pts on drugs
that prolong , interval $ as it predisposes topolymorphic V, 0 ,orsade de pointes
1ypo2alemia * - m)B05 $ >ymptomatic
"linical Features
7/26/2019 Approach to Diagnosis of Hypokalemia
20/44
Digitalis %ntoxication $ ventricular extrasystoles
ventricular tachycardia
ventricular fibrillation
partialcomplete 4V bloc2bradycardia
atrial flutter
atrial fibrillation
Ventricular arrhythmias $ tachycardia 0 fibrillation
"ardiac
7/26/2019 Approach to Diagnosis of Hypokalemia
21/44
6atigue
Myalgia
Muscular =ea2ness involving lo=er limbs
>evere 1ypo2alemia $
+aralysis extremities '
?ea2ness of respiratory muscles dyspnea '
Rhabdomyolysis exercise induced'
&euro'muscular
7/26/2019 Approach to Diagnosis of Hypokalemia
22/44
Constipation
+aralytic ileus
(astro'intestinal
7/26/2019 Approach to Diagnosis of Hypokalemia
23/44
Chronic interstitial nephritis
d0t functional decrease in renal blood flo= , >egment
development of prominent u =aves
>evere hypo2alemia $ increased amplitude of p =ave
increased R> duration
>.+otassium
asic In*estigations
7/26/2019 Approach to Diagnosis of Hypokalemia
28/44
In*estigations ) etiologyErinary "#
,,":
Erinary Chloride
C;C+eripheral >mear
4;:
)chocardiogram
Cardiac )nzymes
>erum aldosterone
>erum renin
E>: 4bdomen
C, 0 MR% 4bdomen
6;> 0 ++;> 0 Erine "etones
,>1 0 free ,- 0 free ,
Colonoscopy 0 8:Dscopy
7/26/2019 Approach to Diagnosis of Hypokalemia
29/44
:rossly due to
Decreased net inta2e
>hift into cells
%ncreased net loss
Diagnosis ) #tiology
7/26/2019 Approach to Diagnosis of Hypokalemia
30/44
7/26/2019 Approach to Diagnosis of Hypokalemia
31/44
8ccurs in patients =ith extreme leu2ocytosis
eg $ in myeloproliferative disorders
%nvitro ?;C upta2e potassium =ithin the test tube
3ot associated =ith any internal 0 external potassium
balance
!purious Hypokalemia
7/26/2019 Approach to Diagnosis of Hypokalemia
32/44
>tarvation
Clay ingestion binds to dietary "# & %ron '
Decreased Intake
7/26/2019 Approach to Diagnosis of Hypokalemia
33/44
4cid < ;ase >tatus $Metabolic 4l2alosis
1ormonal $ %ncreased %nsulin
%ncreased ;eta 4drenergic activity
Drugs $ ;eta agonists
,heophylline
;arium %ntoxicationChloroBuine
Calcium Channel ;loc2ers
ranscellular shifts
7/26/2019 Approach to Diagnosis of Hypokalemia
34/44
Catecholamine release associated =ith $
4sthma
C8+D < exacerbations
1eart failure
Myocardial infarction 0 angina
Drug =ithdra=al syndrome < alcohol 0 narcotics 0 barbiturates
ranscellular shift
7/26/2019 Approach to Diagnosis of Hypokalemia
35/44
%nsulin administration < for treatment of D"4
Refeeding >yndrome
1ypo2alemic +eriodic +aralysis
,hyrotoxic +eriodic +aralysis
,reatment of anemia $ Vit ;( 0 6olic acid deficiency
Ese of :M < C>6 in patients =ith 3eutropenia
ranscellular shift
7/26/2019 Approach to Diagnosis of Hypokalemia
36/44
Decreased total body "#Decreased inta2eRenal loss of "#)xtra renal loss of "#
7/26/2019 Approach to Diagnosis of Hypokalemia
37/44
Erinary "#$ @ m)B05< Renal loss
Erinary " # $ * m)B05< )xtrarenal loss
,,": $ ,ranstubular +otassium :radient
Erine "# 0 +lasma "# '
Erine 8sm 0 +lasma 8sm '
,,": $ Renal loss $ @
)xtra renal loss $ *
%enal ,s #$tra renal loss
7/26/2019 Approach to Diagnosis of Hypokalemia
38/44
#$tra %enal -ossErinary "# * Metabolic 4cidosisMetabolic 4l2alosis
7/26/2019 Approach to Diagnosis of Hypokalemia
39/44
Erinary loss "# @ Metabolic 4cidosisErinary chloride levelErinary chloride levelMetabolic 4l2alosisErinary chloride level
%enal -oss
7/26/2019 Approach to Diagnosis of Hypokalemia
40/44
4mphotericin ; $ tubular damage
increased excretion of "#
4minoglycosides $ renal =asting of "#
,hiazides7 6urosemide7 4cetazolamide $ renal loss "#
Cisplatin
1F+8M4:3)>)M%4 $ >ignificant renal "# =asting
%enal loss ' Drugs
%enal -oss + .etabolic
7/26/2019 Approach to Diagnosis of Hypokalemia
41/44
Erinary Chloride
%enal -oss + .etabolicAlkalosis
7/26/2019 Approach to Diagnosis of Hypokalemia
42/44
1igh $ ;artter71igh $ ;artter71,3 7 %ncreased )C61igh $ ;artter71igh $ ;artter7
%enal loss +/rine "l 0 12 m#34-
7/26/2019 Approach to Diagnosis of Hypokalemia
43/44
RENIN HIGHALD HIGH
RENIN LOWALD HIGH
LOW RENINLOW ALD
R4> +rimary 1yperaldosteronism 38RM45 C8R,%>85 $
Malignant 1,3 :lucorticoid remediable 1,3 )xogenous mineralocorticoid
Renin >ecreting ,umor 5iddles syndrome
58? C8R,%>85 $
4drenogenital syndrome
1%:1 C8R,%>85 $
6amilial :lucocorticoidResistance
7/26/2019 Approach to Diagnosis of Hypokalemia
44/44
HA&K 5O/