The situation when the serum potassium level is below 3.5 mEq/L is called hypokalemia. Generally, hypokalemia is caused due to potassium loss from urinary tract and sweating a lot, although decreased potassium consumption and increased intracellular translocation can also lead to hypokalemia. The cardiovascular and neuromuscular systems are negatively impacted through hypokalemia. In the present report, our objective is to present a 48-year-old female patient admitted with paralysis secondary to hypokalemia, who was diagnosed with distal type 1 renal tubular acidosis (RTA) secondary to Sjogren’s syndrome (SS).
Potassium is highly essential for the body, and 98% of the entire body potassium is situated in intracellular compartment. Intracellular and extracellular potassium ratio is a vital element in making out the capacity of the cellular membrane potentials. Due to this, minimal changes in the extracellular potassium level may lead to substantial damage in certain organ systems.
The case where the serum potassium level is below 3.5 mEq/l is called hypokalemia. Potassium level of 2.53m Eq/L is moderate hypokalemia, while severe hypokalemia is defined as potassium level below 2.5m Eq/L. Hypokalemia may present significant clinical signs in various organ systems including cardiovascular systems. Moderate hypokalemia is generally asymptomatic. However, severe hypokalemia, which is not highly prevalent, may be associated with mortality and morbidity. This may lead to skeletal muscle cramps, hyporeflexia, etc. Potassium loss from urinary tract and sweating a lot are some of the general causes of hypokalemia. That said, decreased potassium consumption and increased translocation can also pave the way for hypokalemia.
Being an autoimmune disease, Sjogren’s syndrome has glandular and extraglandular manifestations. Tubulointerstitial nephritis (TIN) is the major renal association with primary Sjogren syndrome (pSS). TIN can present as distal renal tubular acidosis (RTA), proximal tubular dysfunction, etc. RTA is more widespread in middle-aged women. Hypokalemic paralysis is the first symptom in seven percent of patients having Sjogren’s syndrome.
This report consists of a case with symptoms associated with severe hypokalemia; type 1 distal renal tubular acidosis secondary to Sjogren’s syndrome was found out as causative etiology.
A 48-year middle-aged lady, with hypothyroidism, spine tb (ATT completed 10 years ago) presented to ER with the following complaints: Right leg pain for 2 days, weakness of b/l upper limb and lower limb X 1hour, and generalised myalgia X6 months. Her past history: Last year, the patient had H/O recurrent bone pain for which there was evaluation with DEXA scan that reveals: osteopenia and h/o recurrent abdomen pain diagnosed as nephrolithiasis, which was treated conservatively 1 year ago.
The patient took WYSLONE in the past for her bone pain. Vital parameters : heart rate :66bpm, bp :110/70mmhg ,spo2 : 99% (r/a) , rr : 18 cycles/min ,cbg : 120mg/dl , gcs 15 /15 , temp : afebrille. general examination: Thin built, dry tongue. Nervous system examination included flaccidquadriparesis (powergrade 3/5inproximal muscles and 4+/5 in distal muscle area of the upper and lower limbs) with intense tendon reflexes and plantar reflexes not able to bring out.. Sensory system : intact. other systemic examination : normal.
The initial differential diagnosis of acute onset quadriparesis without alteration of sensorium or sensory or bladder-bowel affection would include: • Electrolyte disturbances: hypokalemia, hyperkalemia, hypercalcemia, hyper- or hypo-natremia, hypophosphatemia, and hypermagnesemia • Central nervous system (CNS) disorders: transverse myelitis, ischemic or traumatic cord lesions / Guillain-Barre syndrome (GBS) • Disorders present in the neuromuscular junction: myasthenia gravis, Lambert-Eaton syndrome • Muscle disorders: Channelopathies and myopathies • Systemic envenomation: Snake bite, tick paralysis or Scorpion sting
In an emergency situation for the patient with flaccid quadriparesis and no upper motor neuron signs, initial laboratory evaluation should include determination of serum electrolyte levels (Na, K, Ca, Mg, PO 4sub ), as these derangements are often readily correctable. Dyselectrolytemias can also produce ECG changes and cardiac rhythm abnormalities. If electrolytes are normal, further testing should be on the lines of the other diagnostic possibilities entertained: Electromyography (EMG) or nerve conduction velocity (NCV) study and lumbar puncture for suspected GBS; cervical cord MRI for lesions in the CNS, repetitive nerve conduction study for myasthenia and muscle enzymes for myopathy. Myasthenic weakness responds well to edrophonium/ neostigmine, and this could be used as a diagnostic tool.
Ecg Finding : Sinus rhythm, with flattened t waves , prominent u wave.
MRI Brain : No acute haemorhage / infarct.
Treatment : With the background of hypokalemia, hypokalemia treatment is initiated.
In the emergency department, the patient was managed with intravenous potassium replacement INJ.KCL40MEQIN500MLNS. Over 4 hours, despite providing IV potassium supplementation, the patient’s serum potassium levels remained 2.05, serum calcium:7.84, serum magnesium:1.8,USG abdomen: Left non-obstructive calculi & left medullary nephrocalcinosis. The patient was given intravenous potassium supplementation at the rate of 10 meq/hour through a central line and taken the intentsive care unit, where there was continuation of treatment. Serial monitoring of potassium level was carried out. Serum potassium levels at 12,24, 36, and 48 hours after starting of treatment were 2.59 mmol/L, 3.35 mmol/L, and 3.70mmol/L, 4.13 mmol/L, respectively. There was the provision of intravenous magnesium supplementation and injection sodium bicarbonate. After 36 hours of treatment, her clinical condition improved significantly with normalization of the muscle power.
There was the urinary pH of 7.0, negative urine culture, no past record of diuretic usage, vomiting, and diarrhea, the normal anion-gap metabolic acidosis in a patient with extreme hypokalemia (serum potassium 1.7 mmol/L). The fitting response to renal K+ secretion is to excrete less than 15 mmol/d of K+ in the urine. A rapid and simple test was designed to evaluate the driving force for net K+ secretion is the transtubular K+ concentration gradient (TTKG). The ratio of the K+ concentration in the lumen of the collecting duct to that in peri-tubular capillaries or plasma is the TTKG. Hypokalemia with a TTKG greater than 4 suggests renal K+ loss due to increased distal K+ secretion. TTKG value is 14mmol/day of k+ in the urine. And the diagnosis of renal tubular acidosis is made.
In our case, availability of hypokalemia, renal calculi and hyperchloremic metabolic acidosis, urinary pH of 7 and non-presence of a positive familial history were all suggestive for type 1 distal RTA. Hypokalemia is the most widely found electrolyte disturbance. The severity of hypokalemia has connection with the signs and symptoms. There are possibilities of periodic paralysis in the case of hypokalemia.
Hypokalemic periodic paralysis may either be primary or secondary to thyrotoxicosis, primary hyperaldosteronism, distal RTA, gastrointestinal damages, and barium intoxication. Hypokalemic periodic paralysis that is secondary to RTA is not frequently observed .Besides the treatment of the pathology leading to distal RTA, HCO3 and K+ replacements are also needed. More observations from the patient’s history showed that she had a history of B/L paratoid swelling a decade ago. For this, the patient was treated with oral steroids, which was the driving force us to assess the possibility of autoimmune disorder. Autoimmune panel showed significantly raised titers of ANA 3+, anti-Ro/SSA and anti-La/SSB antibodies and demonstrated Sjögren’s syndrome. The underlying reason for the clinical problems is Sjögren’s syndrome
SS is a chronic and autoimmune disease with lymphocytic infiltration of every exocrine glands. When there is a fundamental patholody it is a primary SS. There is a fundamental pathology including systemic lupus erythematosus and rheumatoid arthritis in secondary SS. SS is nine times widespread in females. Though it is commonly prevalent at over 40 to 50 years of age, it can be present in all ages.
This is generally an autoimmune exocrinopathy impacting several body systems and organs. However, it is widely related to dry eye and mouth. American-European Consensus Group set forth the diagnostic criteria which comprises clinical information and laboratory examination values. Defined criteria for primary SS when assessed as per these diagnostic criteria are dry eye as well as mouth for more than 3 months, autoantibodies SS-A and SS-B presence, and positive Schirmer test.
Renal disease is present in approximately 10% of every SS patients. It primarily (33%) takes place in the form of RTA. 90% are type 1 distal RTA. Though there is no knowledge of how SS leads to type 1 distal RTA, it was opined that non-availability or lessened activity of H+-ATP case of intercalated cells situated in collecting tubules of distal nephrone may take part in the pathogenesis. Though there is decreased acidification as well as hyperchloremic metabolic acidosis, distal RTA is represented by urinary pH greater than 5.5. Distal RTA can either be primary (either idiopathic or inherited) or secondary. Secondary distal RTA takes place with calcium metabolism disorders etc.
Hypokalemia, hyperchloremic metabolic acidosis, and renal calculi presence and positive familial history absence showed the possibility of type 1 distal RTA secondary to primary SS. Distal RTA may lead to certain renal damages including nephrocalcinosis, chronic interstitial nephritis etc.
The widely present electrolyte disturbance in distal RTA is hypokalemia. Signs are symptoms are associated with the seriousness of the disorder. Periodic paralysis due to hypokalemia may be primary or secondary to primary hyperaldosteronism, gastrointestinal disorders, barium intoxication etc.
Hypokalemic periodic paralysis that is secondary to RTA is not frequently observed. Besides the treatment of the pathology leading to distal RTA, HCO3 and K_ replacements are needed. Control of primary SS is symptomatic. The pressing need will be to reverse the severe hypokalemia when the patient has it in an acute setting. This will be done with intravenous potassium supplementation, followed by rectification of the underlying acidosis. For most of the patients, long-term usage of potassium supplementation might be needed. Muscarinic agonists are suggested for the oral dryness treatment, and to some extent, ocular dryness. Gabapentin, pregabalin, or duloxetine are used to treat patients with primary Sjogren’s syndrome. Blend of corticosteroids and other immunosuppressive drugs has been shown to slow the advancement of renal destruction e in Sjögren’s syndrome, though no immunomodulatory drug has been demonstrated to be effective in primary SS. The generally used agents comprise hydroxychloroquine, prednisone, methotrexate etc. Certain biologic agents have been seriously observed in primary SS, and none have shown substantial efficacy in various studies.
There may be a different clinical presentation for Sjogren’s syndrome, but a case with renal symptoms in the form of hypokalemia as the initial symptom might lead to confusion in diagnosis. This case stresses on the significance of high index of doubt for possibility of Sjogren’s syndrome, particularly in the middle-aged females, who have hypokalemia and metabolic acidosis. In summary, examination of fundamental causes is needed and distal RTA secondary to SS be eliminated in patients having periodic paralysis secondary to hypokalemia.
1.N. Bossini, S. Savoldi, F. Franceschini et al., “Clinical and morphological features of kidney involvement in primary Sjögren’s syndrome,” Nephrology Dialysis Transplantation, vol. 16, no. 12, pp. 2328–2336, 2001.
3.Fox PC. Autoimmune disease and Sjogren’s syndrome. Ann NY Acad Sci. 2007;1098:S15-21.
4.doi pubmedSinger GG, Brenner BM. Fluid and electrolyte disturbances. In: Braunwald E, Fauci AS, Kasper DL, et al, eds. Harrison’s principles of internal medicine. 15th ed. New York: Mc Graw Hill; 2001. p. 279-283.
Dr. Jothi Meena MRCEM Resident Kauvery Hospital
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