Tag: Gitelman

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Metabolic alkalosis and hypokalemia go together like Phineas and Ferb

This is one of my favorite lectures. It starts with Izzy getting fired on Grey’s Anatomy to the metabolic consequences of crack cocaine in dialysis patients to the imaginary monogenic diseases of Ethan Hawke and Denzel Washington. Metabolic alkalosis is a topic that is rarely taught at all. This lecture goes deep tying metabolic alkalosis to potassium handling (as does the kidney). The lecture covers a lot of useful kidney physiology. In addition to metabolic alkalosis it covers some of the salt wasting nephropathies and monogenic causes of hypertension.

Keynote | PDF

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Pregnant Gitelman Patient follow-up

Last week I posted on my pregnant patient who has Gitelman’s Syndrome. I am managing her with amiloride and a mixture of oral potassium and a mixture of oral and IV magnesium.

I received the following letter from a reader who went through a similar experience:

I am not a doctor, but I have Gitelman’s, and 16 years ago, was pregnant and ended up having to go on amiloride at the start of my second trimester, because my potassium and magnesium levels just tanked.   Being part of proving the track record on the viability of amiloride in pregnancy was a scary time, I tell you what.  Your patient’s experiences are similar to mine, though I did not require the magnesium IVs she apparently does during gestation. 

The great news is my son turned out healthy, and without any sign of potassium disorders of any sort, so far as we can tell at nearly 16.  He’s healthy, bright, nearly 6 ft – no indication at this time  that he was harmed in any way by the fetal exposure to amiloride. 

And another point to pass along – after he was born, I had my breast milk checked for traces of amiloride, and it passed whatever screens were applied. Therefore I nursed him for about 9 months, though I supplemented with formula.  It was an acceptable risk for me – since I know the literature does not record any data on nursing while on amiloride, I thought I’d pass along one uncontrolled anecdote for you to ponder. [Note: on further communication the patient clarified that she did not take amiloride during breast feeding] 

Anyway, please pass this information along to your patient – I am sure it will help her peace of mind to know another successful long term outcome.  It was a scary time for me, and without the widespread use of Internet back in 1995, the only piece of mind I got was by tracking down Dr. Almeida, who wrote the 1989 paper about Gitelman’s in pregnancy.  I spoke to one of his nurses to see if they could give me some info on long term followup on the baby, but the mother had disappeared after giving birth, and they had nothing to report.    

Best of luck to your patient – I know what she’s going through. 

Final note for your patient going forward: Getting my levels back up after the birth was a bit of a challenge, I recall.  But many of the details have been lost to time and the fog of war, I’m afraid – I will just say that the first month post-partum was pretty rough on me.

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Gitelman syndrome and Pregnancy

One of my Gitelman patients (whom I kidding, “one of my Gitelman patients”, how about “my only Gitelman patient”) finally got pregnant. We had been managing her with amiloride and a truck load of oral potassium and magnesium supplements. I was shocked to find that amiloride is acceptable in pregnancy with a track record of successful births. Prior to starting amiloride the patient was taking twenty-eight 20 mEq pills of KCl a day. She abandoned her prior nephrologists when she was told to further increase her potassium pills.

from UpToDate

We are now using magnesium sulfate infusions 4 grams twice a week to keep her magnesium north of zero. She was able to keep her magnesium around 1.4 with oral supplements and amiloride prior to being pregnant but now, despite 8 grams of weekly IV magnesium her magnesium is sitting around 1.1. This probably represents one of downsides of the up-regulated GFR of pregnancy.

Interestingly, she saw her labs and saw that her sodium was 132. Modest hyponatremia is a normal finding in pregnancy, so she decided to increase her dietary sodium intake. Bad move, increased renal sodium loads increases renal magnesium losses. Her serum mag fell 30% to 0.8.

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The highest aldosterone I have ever seen

Patient came to me with hypokalemia and hypomagnesemia. She had been asymptomatic when she underwent routine pre-op labs for an elective procedure. Her potassium was 2.0 and the magnesium was later discovered to be 0.9 mmol/L.

She had been treated for 5 months with supplemental potassium and magnesium before she found her way into my office.

During her initial work-up we found:

  • Aldosterone: 61.2
  • Renin: 12.4
  • Trans-tubular potassium gradient: 15.98
  • Diuretic screen: negative
  • 24-hour urine calcium: 57 mmol

Her blood pressure was 120s over 80s on 5 mg of amiloride daily. Her volume status appeared essentially normal.

No renal vascualr disease by MRA, normal CT scan of the abdomen (no renin producing tumor). She was not on aldactone.

Diagnosis: Gitelman’s syndrome.

The principle characteristics of Gitelman’s are: low potassium, low magnesium, initially presenting in adolescence or adulthood. Patients have normal growth. Blood pressure is low. When I first learned about Bartter’s and Gitelman’s I imagined them as congentital diuretics:

  • Bartter’s is congenital Lasix
  • Gitelman’s is congenital HCTZ
The conditions can be understood nearly completely with this crude model. They both have low blood pressure as can be expected from a diuretic-like action. The low blood pressure triggers the renin-angiotensin-aldosterone system resulting in high plasma levels of renin and aldosteronism. In primary hyperaldosteronism, renin is suppressed.
Increased distal delivery of sodium along with increased aldosterone levels leads to increased potassium and hydrogen wasting leading to metabolic alkalosis and hypokalemia.

The two diseases differ in a few areas. Bartter’s results in decreased concentrating ability while concentrating ability is generally intact in Gitelman’s. This is predictable as the Loop of Henle is the engine which drives urinary concentrating and diluting ability. Gitelman’s has a low urinary calcium just as found with thiazides.

What was remarkable to me, was how high the aldosterone level was. This is in a patient without adrenal disease, the aldosterone is released in response to normal stimuli, volume depletion in this case. In primary aldosteronism, where there is autonomous secretion of aldosterone by a tumor, the aldosterone level typically rises to 20-30. But in this patient, where the adrenal gland is intact, the aldo level goes bonkers to almost 70.

Incredible.