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📢Tweetorial alert!
Hey #medtwitter! Have you checked out @TheskeletonKG latest case - a rare cause of hypokalemia?
renalfellow.org/2021/05/22/ske…
Let's go through it together
#NSMC #FOAMed #NephTwitter @NSMCInternship
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A 32-year-old woman, presented to the clinic with B/L lower extremity weakness & upper limb cramping for 2 weeks. Motor power 3/5 in lower limbs & 4/5 in upper limbs. B/L ankle & knee jerk reflexes were absent. She had 1 such episode in the past which recovered spontaneously.
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She denied using any medications before the onset of symptoms. She had no family history of kidney disease. Her labs showed ⏬K⏬Mg, normal TSH and negative ANA. USG of the abdomen was normal.
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⚠️ Before evaluating hypokalemia, life threatening complications such as arrhythmias and paralysis should be looked for. If present, it should be treated with IV potassium(K) & magnesium(Mg)
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The next step in evaluating hypokalemia is differentiating kidney K wasting from other causes.
📌A urine K/Cr ratio >15 mEq/g suggests urinary losses.
⚡️A K/Cr ratio of 23 mEq/g in this patient identifies kidney as the culprit of K loss.
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With a BP of 106/70 mm Hg, we checked the acid base status next. The presence of metabolic alkalosis narrowed down the diagnosis to either vomiting/ diuretic use/ Gitelman syndrome (GS) or Bartter syndrome(BS)
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📌Urine chloride levels <10 mmol/L indicate GI losses.
📌Urine Ca/Cr ratio <0.07 mg/mg is suggestive of hypocalciuria & is seen in GS & thiazide use. A ratio >0.20 is seen in Bartter syndrome & with loop diuretics suggesting hypercalciuria.
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⚡️Increased urine chloride excretion of 80 mEq/L and a Ca/Cr ratio of 0.04 mg/mg in our patient, with no history of thiazide use narrowed down our diagnosis to GS.
⚠️ Be careful of those units when working on those computations! ⚠️
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Why do we think it's Gitelman syndrome? She had
🔸Hypokalemia
🔸Hypomagnesemia
🔸Normal BP
🔸Metabolic alkalosis
🔸Hypocalciuria
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🧬GS is a rare autosomal recessive salt-losing tubulopathy with a prevalence of 1- 10 in 40,000, estimated to be higher in Asians. It occurs due to inactivating mutations in the SLC12A3 gene that encodes thiazide-sensitive sodium-chloride cotransporter in the distal tubule.
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Patients with GS usually present in late childhood/ early adulthood. Although the majority of them have mild or nonspecific symptoms, severe life-threatening complications can rarely occur @goKDIGO @Kidney_Int
kidney-international.org/article/S0085-…
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The criteria to diagnose Gitelman syndrome includes clinical, biochemical parameters often supported by genetic testing.
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The differential diagnosis of GS include
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All of the above!
📌Thiazide use is associated with variable Cl excretion & a positive urine assay for diuretics
📌cBS occurs at a younger age, with failure to thrive, polyuria with usually normal Mg levels
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📌HNF1B mutations associated with MODY, early CKD, family history, abnormal liver enzymes, renal/urogenital malformations
📌KCNJ10 mutations present with EAST syndrome
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Treatment includes
🔹Electrolyte replacement - K & Mg, preferably Cl salts
🔹K & Mg rich food
🔹Liberal salt intake
🔹In persistent hypokalemia, K sparing diuretics, RAASi, NSAIDS may be used with caution
🎯Target K levels- 3.0 mEq/L
🎯Target Mg levels- 1.4 mg/dl @goKDIGO
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Side effects of the drugs include abdominal pain, diarrhoea & gastritis. Patient should be followed up regularly til near normal/stable levels of K & Mg is achieved. At least an annual follow up is recommended thereafter, to monitor potential complications & disease evolution
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Long term management include
📌Educating patients & caregivers about GS & its outcome
📌Individualised measures to improve school/work performance & QOL
⭐Various groups help create awareness & offer support to pts with GS @gitelmansuk gitelmansyndrome.co.uk
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To Summarize
🔑GS presents with⏬K⏬Mg, met alkalosis, hypocalciuria, normal BP
🔑Urine K/Cr ratio >15 mEq/g= kidney K loss
🔑Urine Ca/Cr ratio <0.07 mg/mg= GS/thiazides & >0.20= BS/loop diuretic
🔑Bialleic inactivating mutation of SLC12A3= GS
🔑Treatment-K & Mg replacement
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Check out this fabulous VA by @NSMC intern @nephromythri Thank you to the @TheSkeletonKG members,@dr_missyhanna @SRameshMD for helping me put this case together! Til next month! 🏴☠️
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