Hi #medtwitter. We are back with our monthly case. This time we will be deconstructing Phosphorus. Join us as we diagnose and manage Hypophosphatemia!! #tweetorial #FOAMED #nephtwitter @TheSkeletonKG @NSMCInternship 
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41-year-old female with a history of systemic lupus erythematosus, Raynauds phenomenon, migraines, and depression is referred to the nephrology clinic for refractory hypophosphatemia.
⚡Two weeks ago, she was seen in the ER for a Phos of 1.1 mg/dL.
⚡Repeat labs shown below
41-year-old female with a history of systemic lupus erythematosus, Raynauds phenomenon, migraines, and depression is referred to the nephrology clinic for refractory hypophosphatemia.
⚡Two weeks ago, she was seen in the ER for a Phos of 1.1 mg/dL.
⚡Repeat labs shown below
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📌Repeat labs showed a phos level of 1.3 mg/dL despite phos repletion. What would you do at this point?
📌Repeat labs showed a phos level of 1.3 mg/dL despite phos repletion. What would you do at this point?
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⚡I think it's important to dwell more into her history. What are the symptoms of low phosphorus?
⚡I think it's important to dwell more into her history. What are the symptoms of low phosphorus?
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Our patient had all the above-mentioned symptoms for the last ↗️ 3 months.
📌 Symptoms began after she received a dose of⚡ IV Ferric Carboxymaltose 3 months ago for iron deficiency.
Our patient had all the above-mentioned symptoms for the last ↗️ 3 months.
📌 Symptoms began after she received a dose of⚡ IV Ferric Carboxymaltose 3 months ago for iron deficiency.
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What are your differentials at this point?
What are your differentials at this point?
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What further studies do you want?
⚡More details on the labs in our case
renalfellow.org/2020/06/17/ske…
What further studies do you want?
⚡More details on the labs in our case
renalfellow.org/2020/06/17/ske…
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Her FEPO4 was 📌 32.9%. Quick recap to FEPO4 calculation
Her FEPO4 was 📌 32.9%. Quick recap to FEPO4 calculation
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📌Once we have established urine phosphorus wasting, what is your approach and which labs do you want?
📌Once we have established urine phosphorus wasting, what is your approach and which labs do you want?
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📌Our approach to Urine phosphorus wasting
📌Our approach to Urine phosphorus wasting
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Based on the algorithm we checked the following labs
Based on the algorithm we checked the following labs
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Lets review Phos absorption.
⚡ PCT absorbs 80-95% of phosphorus 📌 NaPi2a 📌NaPi2c 📌 PiT2 cotransporters.
⚡PTH and FGF23 are✅ phosphaturic. They 📌downregulate the expression of NaPi2a and 2c. ajkd.org/article/S0272-…
Lets review Phos absorption.
⚡ PCT absorbs 80-95% of phosphorus 📌 NaPi2a 📌NaPi2c 📌 PiT2 cotransporters.
⚡PTH and FGF23 are✅ phosphaturic. They 📌downregulate the expression of NaPi2a and 2c. ajkd.org/article/S0272-…
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📌Knowing what we know about Pi reabsorption, which acid base disorder leads to Hypophos?
📌Knowing what we know about Pi reabsorption, which acid base disorder leads to Hypophos?
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Acute respi alkalosis leads to extracellular CO2 diffusion
⚡Rise in intracellular pH ⚡ increases glycolysis ↗️The requirement for cellular phosphate uptake leads to hypophos.
✅Chronic respi alkalosis is associated with Hyperphosphatemia due to renal resistance to PTH.
Acute respi alkalosis leads to extracellular CO2 diffusion
⚡Rise in intracellular pH ⚡ increases glycolysis ↗️The requirement for cellular phosphate uptake leads to hypophos.
✅Chronic respi alkalosis is associated with Hyperphosphatemia due to renal resistance to PTH.
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⚡In our patient with a normal iPTH, we also checked additional labs.
⚡In our patient with a normal iPTH, we also checked additional labs.
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Lab were suggestive of
⚡ High FGF23 state
⚡Low 1,25 hydroxy Vit D levels.
What effects does FGF23 have?
Lab were suggestive of
⚡ High FGF23 state
⚡Low 1,25 hydroxy Vit D levels.
What effects does FGF23 have?
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That's right. FGF23 leads to all the above mentioned effects.
⚡What disease states are associated with incr FGF23?
That's right. FGF23 leads to all the above mentioned effects.
⚡What disease states are associated with incr FGF23?
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All of the above lead to increase in FGF23 levels !!
Read more about FGF23 and mechanisms as it pertains to ⚡ IV ferric carboxymaltose
nature.com/articles/s4158…
asbmr.onlinelibrary.wiley.com/doi/epdf/10.10…
All of the above lead to increase in FGF23 levels !!
Read more about FGF23 and mechanisms as it pertains to ⚡ IV ferric carboxymaltose
nature.com/articles/s4158…
asbmr.onlinelibrary.wiley.com/doi/epdf/10.10…
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The hypophosphatemia from IV iron infusions peaks↗️around 7 days and may be prolonged lasting over ↗️months after infusions are complete.
The hypophosphatemia from IV iron infusions peaks↗️around 7 days and may be prolonged lasting over ↗️months after infusions are complete.
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Back to our case. We concluded that Ferric carboxymaltose can inhibit FGF23 degradation resulting in increased FGF23 levels, such as seen in our patient.
Back to our case. We concluded that Ferric carboxymaltose can inhibit FGF23 degradation resulting in increased FGF23 levels, such as seen in our patient.
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This amazing visual abstract helps to summarize the case! Read the full post at @RenalFellowNtwk @sopalilla
renalfellow.org/2020/06/17/ske…
This amazing visual abstract helps to summarize the case! Read the full post at @RenalFellowNtwk @sopalilla
renalfellow.org/2020/06/17/ske…
