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|LETTER TO EDITOR
|Year : 2015 | Volume
| Issue : 3 | Page : 446-448
Hypokalemic paralysis as a primary presentation of Fanconi's syndrome and distal renal tubular acidosis in a patient with primary Sjogren's syndrome
Anita Basavaraj, Rohan Ramesh Badave, Manasi Kadam, Deelip Babasaheb Kadam
Department of Medicine, Sassoon General Hospital, Pune, Maharashtra, India
|Date of Web Publication||5-Jun-2015|
Department of Medicine, Sassoon General Hospital, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Basavaraj A, Badave RR, Kadam M, Kadam DB. Hypokalemic paralysis as a primary presentation of Fanconi's syndrome and distal renal tubular acidosis in a patient with primary Sjogren's syndrome. Neurol India 2015;63:446-8
|How to cite this URL:|
Basavaraj A, Badave RR, Kadam M, Kadam DB. Hypokalemic paralysis as a primary presentation of Fanconi's syndrome and distal renal tubular acidosis in a patient with primary Sjogren's syndrome. Neurol India [serial online] 2015 [cited 2020 Sep 29];63:446-8. Available from: http://www.neurologyindia.com/text.asp?2015/63/3/446/158264
Primary Sjogren's Syndrome (pSS) is a disease of the exocrine glands presenting with manifestations related to dry eyes and dry mouth. , Non-exocrine organ systems may also be involved, including the skin, lungs, gastrointestinal tract, central and peripheral nervous system, musculo-skeletal apparatus, and kidney. , Hypokalemic paralysis is a very rare primary presentation of pSS.
We report a case of a 39-year old female patient, a known case of seizure disorder on regular treatment with oral sodium valproate 200mg twice daily and oral phenobarbitone 30 mg twice daily. She presented with sudden onset of quadriparasis that occurred a day prior to her admission. There was no history of trauma, insect or animal bites, loose motions, headache or altered sensorium. She was afebrile with a pulse rate of 78/min in sinus rhythm and a BP of 120/80 mm/Hg. She was shifted to the intensive care unit. On systemic examination, she had hypotonia with grade I power in all four limbs. All deep tendon reflexes were depressed and the superficial reflexes including the plantar reflex were absent. Her neck holding was, however, present. The systemic examination was within normal limits.
On laboratory investigation, her metabolic investigations were within normal limits except for a low serum potassium (2.5 meq/l). Her electrocardiogram showed an ST depression which was concave upwards; and, the presence of U waves, suggestive of hypokalemia. The blood gas analysis was suggestive of a non-anion gap metabolic acidosis with hyperchloremia and hypokalemia. Correction of hypokalemia was done with a slow infusion (over 12 hours) of potassium chloride in normal saline. The patient responded to the correction of hypokalemia with improvement in her power by the third day.
To determine the cause of the non-anion gap metabolic acidosis with hypokalemia (with no gastrointestinal complaints), a urine spot test was done. It showed the urinary pH as being on the higher side, an increased urinary potassium with a positive urinary gap. Further we calculated the transtubular potassium gradient (TTKG). In the cases associated with hypokalemia, the normally urinary TTKG value is less than 4. In our case, it was 28.2 favoring the diagnosis of distal renal tubular acidosis (dRTA). Further urinary analysis showed that she had hyperphosphaturia, hypercalciuria, euglycemic glycosuria and hyperuricosuria. These findings pointed towards the presence of Fanconi's syndrome (FS). The high urinary pH was due to the combination of dRTA and FS.
In search for the cause of dRTA and FS, antinuclear antibody (ANA) level was initially evaluated. It came strongly positive with a titre of 3.07. Further work up revealed positive anti Ro antibodies and anti La antibodies while other antibodies were not detectable. This led to the establishment of the diagnosis of Sjogren's syndrome. She had a positive Schirmer's test, showing wetting of Whatman number 41 filter paper of less than 5 mm in both eyes. A detailed ophthalmic evaluation revealed a short tear break up time test with fluorescent staining showing dry patches at 4 seconds with an ocular staining score of 3. According to the American College of Rheumatology classification criteria, our patient had the presence of a primary Sjogren's syndrome. She was managed with sodium bicarbonate in a dose of 1-3 mmol/kg per day. She was further treated with methyl prednisolone one gram per day for five days. Thereafter, she was treated with cyclophosphamide at a dose of 50 mg thrice a day, a high phosphate diet and oral potassium supplementation. With this treatment, she improved to grade IV power in both upper and lower limbs.
Hypokalemic paralysis is an important cause of acute flaccid paralysis, but it has a number of clinical differentials like the Guillain Barré syndrome, acute transverse myelitis, myositis, poliomyelitis, porphyria, hyperaldosteronism, thyrotoxicosis, renal tubular acidosis (RTA), Gitelman syndrome, barium poisoning, and diarrhea. ,, It is important to differentiate familial periodic paralysis (FPP) from RTA as both the diseases may have a similar clinical picture during an acute attack; however, administration of sodium bicarbonate in FPP would facilitate intracellular potassium flux and fatal hypokalemia may be precipitated.  Our patient has no family history of related manifestations. Recognition of the underlying causes is essential for the appropriate management of patients with hypokalemic paralysis.
There have been few case reports where hypokalemic periodic paralysis has been investigated and has led to the diagnosis of Sjogren's syndrome. The first such case was reported as early as in 1981. India's first case was reported in 1996 by Thomas et al. from CMC Vellore.  Rao et al. in 2006 studied 31 cases of hypokalemic periodic paralysis where 3 cases had a Sjogren's syndrome.  This indicates that 10% of people with hypokalemic periodic paralysis can have Sjogren's syndrome, which if diagnosed early, has more management options available.
In conclusion, the kidney involvement in pSS can uncommonly present as hypokalemic paralysis in the absence of significant Sicca symptoms; or, the renal manifestations may precede Sicca symptoms. Sjögren's syndrome should be suspected in any patient presenting with hypokalemic paralysis in the presence of RTA, even in the absence of the Sicca syndrome. Early recognition of the presence of hypokalemic paralysis due to the underlying SS-related RTA with institution of prompt therapy, not only helps in treating the potentially life-threatening hypokalemia, but also improves the renal outcome.
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